Witnesses of Virginia Tech Massacre Paint Grim, Grisly Picture of the Horror That Gripped Campus

Witnesses continued to paint a stark, grisly picture of the horror that unfolded Monday at Virginia Tech a day after a student gunman opened fire on the campus and apparently killed 32 people before committing suicide.

Student Melanie Swift was in Norris Hall, the engineering building where most of the murders took place, when 23-year-old Cho Seung-Hui — a South Korean immigrant who was enrolled as a senior at the Blacksburg, Va., school — began mowing people down with two handguns.

"We started hearing shooting. In the meantime, we start hearing screams," Swift told FOX News on Tuesday. "The teacher is just trying to keep us calm. We heard, 'Call 911!' We were so confused about what was going on."

She said at a certain point, the mayhem swelled and she and her classmates began sprinting through the building in an attempt to escape.

"We were running. Girls were panicking, starting to cry," she told FOX. "Everyone was like, get away from the windows. The shooting was like 15 minutes — like this constant bang, bang, bang. Then we heard voices in the hallway: That was probably the scariest. We didn't know who was out there."

Those in the room silenced each other so the gunman wouldn't know they were there and then managed to flee Norris Hall, according to Swift.

Though she didn't see anything as she was leaving, the scent of smoking guns wafted through the corridors.

"The whole second floor just smelled of smoke and gunfire. You could tell there was a lot of shooting," Swift remembered.

When it was all over, Cho was responsible not only for the worst-ever school shooting in the United States but the deadliest massacre of any kind on American soil in modern history.

Another student, Derek O'Dell, was in a room across the hall from where Cho began his killing spree. At first, he said, everyone thought the noises they were hearing were the hammering sounds of construction.

"We didn't make that much of it," said O'Dell, who was hit in the right arm. Then "he entered our room and started shooting people."

Cho first shot the professor in the head before gunning down some of his classmates in the front row, according to O'Dell. Most of the people in that part of the room died, he said. O'Dell dove under his desk.

"I knew I was shot, but I knew I had to barricade the door 'cause he might return and shoot the rest of us," he said. Those who weren't gravely wounded used anything they could —- shoes, feet, hands — to block the door.

"It was pure carnage — blood everywhere, blood spewed against the walls," O'Dell remembered.

He described the gunman as an Asian male, about 6 feet tall with short hair, wearing a leather jacket, an ammunition belt and a hat. Cho — a resident alien and an English major who was set to graduate in a few weeks — uttered no words or sounds as he fired. O'Dell said he only saw one gun, which he witnessed Cho reloading once while he was in his classroom.

"It was sort of an eerie silence between the gunshots," O'Dell said. "He didn't say anything. [There was] no screaming, no yelling."

One of his fellow students, Trey Perkins, was among only two in the class of at least 15 who weren't struck.

Perkins told FOX News he flipped some desks over on their sides to create an obstacle between the gunman and the students who hadn't fallen in the first spray of bullets. He considered jumping out a window, he said, but he didn't want to abandon the wounded.

"So many people were laying in the room and still conscious and I didn't just want to leave them all there," Perkins told FOX. "So we tried to block the door."

He guessed that only about six of them made it out alive.

Questions surfaced about why students didn't try to rush the gunman and force him to the ground, but Perkins said there wasn't a way to do it safely.

"He came in with two guns and he immediately opened fire," he said. "I would say within 10 seconds, there were so many people down. He wasn't in any location to try to tackle him. I thought about getting up to try to do it, but he was just shooting. There was no way to get over the desks."

Student Sara Thompson was taking a test one floor above where the massacre happened, and echoed other accounts that described the constant gunfire as sounding like a jackhammer during construction.

When she left class after finishing the test and went down a floor, Thompson was greeted by the smell of gun powder, a hot floor under her feet and panicked students diving to safety in the stairwell. She put two and two together.

But Thompson said she still hasn't fully grasped what went on.

"For a lot of students it's going to take a while to get over what happened," she told FOX.

Though O'Dell's memories of Monday's bloodbath are vivid, he hopes that one day, he'll remember none of it.

"It's almost better if I can forget it all," he said. "Just to replay those images in my head, it gives me terrors."