Police say they've preliminarily identified a gunman who massacred 32 people Monday at Virginia Tech in the deadliest shooting rampage in modern U.S. history, cutting down his victims in two attacks two hours apart before the university could grasp what was happening and get the warning out to students.

Virginia Tech Police Chief Wendell Flinchum would not release the name of the dead gunman, adding that the investigation was ongoing, and "we want to get it right."

The Chicago Sun-Times reported Monday night that authorities are investigating whether the gunman was a 24-year-old Chinese man who arrived in the U.S. last year on a student visa issued in Shanghai. Police believe three bomb threats on the campus last week may have been attempts by the man to test the campus' security response, the newspaper reported.

List of Victims in Virginia Tech Massacre

Flinchum also would not confirm whether the gunman, responsible for the bloodbath that left 30 dead in the school's Norris Hall classroom building, was the same person who killed two people — a male and a female — two hours earlier in a dormitory on the other side of the sprawling western Virginia campus.

"We have a preliminary ID, but we're not prepared to release it yet. The investigation is ongoing and we are making progress," Flinchum told reporters Monday night, adding that police had questioned a "person of interest" related to the first shooting, and that person was not the dead gunman.

"They're not the same person," the Flinchum said, referring to the person of interest and the gunman. "We are actively pursing all leads, and this investigation will determine whether they [the shootings] are related or not."

Flinchum refused to dismiss the possibility that a co-conspirator or second shooter was involved.

"I'm not saying there's a gunman on the loose," Flinchum said. Ballistics tests will help explain what happened, he said.

Sheree Mixell, a spokeswoman for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, said the evidence was being moved to the agency's national lab in Annandale, Va. At least one firearm was turned over, she said.

Mixell would not comment on what types of weapons were used or whether the gunman was a student.

A law enforcement official, speaking on condition of anonymity because the investigation was incomplete, said that the gunman had two pistols and multiple clips of ammunition. The student newspaper reported that police had sent two guns to the state police crime lab for forensic testing.

In all, the death toll of the two shootings was 33, including the gunman. At least 15 people were wounded, four seriously.

The methodical mass murder forever stamped tragedy on the picturesque campus nestled in the western foothills of the Blue Ridge Mountains.

"I'm really at a loss for words to explain or understand the carnage that has visited our campus," Virginia Tech President Charles Steger said.

He also was faced with difficult questions about the university's handling of the emergency and whether it did enough to warn students and protect them after the first burst of gunfire.

Officials defended their actions, with the police chief telling people to "keep in mind that it takes time" to collect all the pieces.

While investigators offered no motive for the attacks, what is known is this:

A gunman opened fire about 7:15 a.m. in the West Ambler Johnston coed dormitory. Virginia Tech and Blacksburg, Va., police were dispatched to the scene and arrived to find the bodies of two people, a male and a female. Based on interviews with residents and witnesses, police identified and questioned a "person of interest." That person was not in custody Monday night, police said.

About two and half hours later, around 9:45 a.m., police received a second 911 call of a shooting at Norris Hall, an Engineering Department classroom building on the other side of the 2,600-acre campus. Officers arriving on the scene found at least two doors chained to prevent the building's occupants from escaping, police said.

Police broke down one door and stormed the building and followed the sounds of the shooting to the second floor when the sounds of gunfire stopped and they found the gunman dead, apparently of a self-inflicted gunshot wound to the head, Flinchum said.

Thirty-one were killed in Norris Hall, including the gunman. At least 26 people were hurt, some seriously.

"It's probably one of the worst things I've seen in my life," Flinchum said, declining to further describe the scene.

Students in Norris Hall jumped from windows in panic.

Alec Calhoun, a 20-year-old junior, said he was in a 9:05 a.m. mechanics class when he and classmates heard a thunderous sound from the classroom next door — "what sounded like an enormous hammer."

Screams followed an instant later, and the banging continued. When students realized the sounds were gunshots, Calhoun said, he started flipping over desks for hiding places. Others dashed to the windows of the second-floor classroom, kicking out the screens and jumping from the ledge of Room 204, he said.

"I must've been the eighth or ninth person who jumped, and I think I was the last," said Calhoun, of Waynesboro, Va. He landed in a bush and ran.

Calhoun said that the two students behind him were shot, but that he believed they survived. Just before he climbed out the window, Calhoun said, he turned to look at the professor, who had stayed behind, perhaps to block the door.

The instructor was killed, he said.

Young people and faculty members carried out some of the wounded themselves, without waiting for ambulances to arrive. Many found themselves trapped behind the chained and padlocked doors. SWAT team members and FBI agents with helmets, flak jackets and assault rifles swarmed over the campus.

Trey Perkins, who was sitting in a German class in Norris Hall, told The Washington Post that the gunman barged into the room at about 9:50 a.m. and opened fire for about a minute and a half, squeezing off 30 shots in all.

The gunman, Perkins said, first shot the professor in the head and then fired on the students. Perkins said the gunman was about 19 years old and had a "very serious but very calm look on his face."

"Everyone hit the floor at that moment," said Perkins, 20, of Yorktown, Va., a sophomore studying mechanical engineering. "And the shots seemed like it lasted forever."

Erin Sheehan, who also was in the German class, told the student newspaper, the Collegiate Times, said she was one of only four of the approximately two dozen people in the class to walk out of the room. The rest were dead or wounded, she said.

"It seemed so strange," Sheehan said. The gunman "peeked in twice, earlier in the lesson, like he was looking for someone, somebody, before he started shooting. But then we all heard something like drilling in the walls, and someone thought they sounded like bullets. That's when we blockaded the door to stop anyone from coming in."

She said the gunman "was just a normal-looking kid, Asian, but he had on a Boy Scout-type outfit. He wore a tan button-up vest, and this black vest, maybe it was for ammo or something."

"I saw bullets hit people's body," Sheehan said. "There was blood everywhere." She added, "My professor, Herr Bishop, I'm not sure if he's alive."

Kevin Tosh, 20, of Rocky Mount, Va., lives three floors above where the shooting occurred, but he said he said he woke up Monday like he usually does, showering and heading to class around 8:45 a.m. He only noticed something was wrong when he saw about one dozen police cars outside the entrance.

“I was in journalism class and somebody got the e-mail,” Tosh said. He said not too long afterward — about 9:45 a.m. or 10 a.m. — there was another e-mail, this one about the second shooting.

Tosh said he had mixed feelings about the speed of the official response.

“I think [the campus police] had it under control. … I thought they did a good job, but I think they could have done better,” said the sophomore communications major.

Lake Singh and his friend Michael Patrick Stone said they were in their dorms Monday morning when campus police began knocking on doors, making sure that anyone who was inside the dorm was locked in their rooms. Outside Singh’s window, he could see Norris Hall.

Singh, 18, of Burke, Va., said he was eating breakfast when he got the e-mail about the shooting. The sophomore aerospace engineering major said he thought it still could just have been part of the investigation into last week’s campus bomb threats. Then he began to see the police activity.

“Guys with M-16s started running across the drill fields,” Singh said. “That’s when I realized it wasn’t just a bomb threat.”

“It scared me,” he added.

The two said they were able to see body bags being removed from Norris Hall.

“It’s something that I know I’m never going to forget,” said Stone, 20, of Bumpass, Va.

Once they were allowed to leave, Stone and Singh said that campus buildings soon began filling up with armor-clad tactical police officers and buildings were closed down.

Despite the confusion and the chaos, the two said there were supportive of the way university officials handled the situation.

“The university did a wonderful job,” said Stone, a sophomore engineering major. Singh agreed. Stone said he believed there was little anyone could have done. Standing outside The Inn at Virginia Tech and Skelton Conference Center, where reporters were staked out, Stone opened his coat and said anyone could hide weapons to do the damage that was done Monday.

“If he’s motivated to do it, he can do it,” Stone said.

The two students said generally, the campus is safe, and last week’s bomb threats at the time seemed like huge news. Now they were going to be taking stock over the next few days, trying to figure out if they knew any of the victims.

“It’s been a hard day. I just hope nobody I know died,” Singh said.

While Singh and Stone felt campus police did their jobs, other students bitterly complained that there were no public-address announcements on campus after the first shots. Many said the first word from the university was an e-mail more than two hours into the rampage — around the time the gunman struck again.

Steger defended the university's handling of the tragedy, saying authorities believed that the shooting at the dorm was a domestic dispute and mistakenly thought the gunman had fled the campus.

"We had no reason to suspect any other incident was going to occur," he said.

Steger emphasized that the university closed off the dorm after the first attack and decided to rely on e-mail and other electronic means to notify members of the university, but with 11,000 people driving onto campus first thing in the morning, it was difficult to get the word out, he said.

Steger said that before the e-mail went out, the university began telephoning resident advisers in the dorms to notify them and sent people to knock on doors to spread the word. Students were warned to stay inside and away from the windows.

"We can only make decisions based on the information you had at the time. You don't have hours to reflect on it," Steger said. He called the massacre a tragedy of "monumental proportions."

Some students and Laura Wedin, a student programs manager at Virginia Tech, said the first notification they got of the shootings came in an e-mail at 9:26 a.m., more than two hours after the first shooting.

The e-mail had few details. It read: "A shooting incident occurred at West Amber Johnston earlier this morning. Police are on the scene and are investigating." The message warned students to be cautious and contact police about anything suspicious.

Everett Good, junior, said of the lack of warning: "Someone's head is definitely going to roll over that."

Edmund Henneke, associate dean of engineering, said he was in the classroom building and he and colleagues had just read the e-mail advisory regarding the first shooting and were discussing it when he heard gunfire. He said moments later SWAT team members rushed them downstairs, but the doors were chained and padlocked from the inside. They left the building through a construction area that had not been locked.

Until Monday, the deadliest mass shooting in modern U.S. history was in Killeen, Texas, in 1991, when George Hennard plowed his pickup truck into a Luby's Cafeteria and shot 23 people to death, then himself.

The massacre Monday took place almost eight years to the day after the Columbine High bloodbath near Littleton, Colo. On April 20, 1999, two teenagers killed 12 fellow students and a teacher before taking their own lives.

Previously, the deadliest campus shooting in U.S. history was a rampage that took place in 1966 at the University of Texas at Austin, where Charles Whitman climbed the clock tower and opened fire with a rifle from the 28th-floor observation deck. He killed 16 people before he was shot to death by police.

Founded in 1872, Virginia Tech is nestled in southwestern Virginia, about 160 miles west of Richmond. With more than 25,000 full-time students, it has the state's largest full-time student population. The school is best known for its engineering school and its powerhouse Hokies football team.

The rampage took place on a brisk spring day, with snow flurries swirling around the campus. The campus is centered around the Drill Field, a grassy field where military cadets — who now represent a fraction of the student body — practice. The dorm and the classroom building are on opposites sides of the Drill Field.

A White House spokesman said President Bush was horrified by the rampage and offered his prayers to the victims and the people of Virginia. "The president believes that there is a right for people to bear arms, but that all laws must be followed," spokeswoman Dana Perino said

After the shootings, all entrances to the campus were closed, and classes were canceled through Tuesday. The university set up a meeting place for families to reunite with their children. It also made counselors available and planned an assembly for Tuesday at the basketball arena.

It was second time in less than a year that the campus was closed because of a shooting.

Last August, the opening day of classes was canceled and the campus closed when an escaped jail inmate allegedly killed a hospital guard off campus and fled to the Tech area. A sheriff's deputy involved in the manhunt was killed on a trail just off campus. The accused gunman, William Morva, faces capital murder charges.

FOX News' Greg Simmons and Catherine Donaldson-Evans, and The Associated Press contributed to this report.