A man with a rifle opened fire at a busy Omaha shopping mall Wednesday, killing eight people before taking his own life, police said. Five others were wounded, two critically.

The killer has been identified as Robert A. Hawkins, age 19 or 20, who left a suicide note stating, "I'm going out in style" and "I'm going to be famous." The man's vehicle was reportedly found in the parking lot.

Hawkins' mother brought the note to the local sheriff's office. She was being questioned by investigators Wednesday night.

Sgt. Teresa Negron said the gunman killed eight people, then apparently killed himself. Authorities gave no motive for the attack and did not know whether he said anything during the rampage.

Friends described Hawkins as "depressed" and said he had quit school several years ago and worked at a series of fast food jobs. He was arrested last month on misdemeanor charges and was expected to appear in court this month.

Officials said Hawkins, clad in military-style clothing, entered the mall just before 2 p.m. Wednesday and began firing off rounds. The rampage sent shoppers and employees running and screaming through the Westroads Mall, barricading themselves in dressing rooms after hearing gunfire. Hawkins was found dead on the third floor of the Von Maur store with a self-inflicted gunshot wound, and his victims were discovered on the second and third floors, police said.

Witnesses said Hawkins fired down on shoppers from a third-floor balcony of the Von Maur store.

"Everybody was scared, and we didn't know what was going on," said Belene Esaw-Kagbara, 31, a Von Maur employee. "We didn't know what to do. I was praying that God protect us."

Mickey Vickory, who worked at Von Maur's third-floor service department, said she heard shots at about 1:50 p.m.

She and her co-workers and customers went into a back closet behind the wrapping room to hide, then emerged about a half-hour later when police shouted to come out with their hands up. As police took them to another part of the mall for safety, they saw the victims.

"We saw the bodies and we saw the blood," she said.

Police received a 911 call from someone inside the mall, and shots could be heard in the background, Negron said. By the time officers arrived six minutes later, the shooting was over, she said.

Shortly after the shooting, which came three weeks before Christmas, a group of shoppers came out of the building with their hands raised. Some were still holding shopping bags.

It was not clear Wednesday night when Hawkins took his own life.

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Another man was taken into custody outside of the mall, but his role in the shooting was not clear.

Two gunshot victims who were treated at Creighton Medical Center died from their wounds, FOX News confirmed, and a third victim being treated there remained in critical condition.

No additional information was available on the other fatalities.

Andrea McMaster, a spokeswoman for the University of Nebraska Medical Center, told FOX News that three shooting victims were being treated there: a 61-year-old man shot in the chest, a 34-year-old man shot in the arm, and a 55-year-old man with a cut to his face. The 61-year-old man was in critical condition and undergoing surgery.

Police had put the Westroads Mall, Omaha's largest shopping mall, on lockdown while it searched for the gunman.

One of the victims was reportedly an elderly man found near an escalator inside Von Maur department store, one of the mall's anchor tenents.

Witnesses described hearing "dozens and dozens" of shots being fired, with one witness saying she heard more than 30 shots.

Shawn Vidlak said he heard four or five rapid shots "like a nail gun." At first he thought it was noise from construction work going on at the mall.

"People started screaming about gunshots," Vidlak said. "I grabbed my wife and kids we got out of there as fast as we could."

A woman who answered the phone at an Old Navy store said 20 to 30 customers were huddled with employees in a back storeroom.

"All we know was people were running and screaming down the hallway by Von Maur saying there was a shooting, and then they locked us down," said the woman, who said her name was Heidi.

Keith Fidler, an employee at Von Maur, said he heard the burst of gunfire, followed by dozens of shots. Fidler said he huddled in the corner of the men's clothing department with about a dozen other employees until police yelled to get out of the store.

Fidler said he did not see the shooting, but saw a person lying by the elevator as he was leaving the store.

Todd Trimpe told FOX News that he saw police apprehend a man, dressed in camouflage, who was hiding under a bus-stop bench outside the mall. Trimpe said the man "stood out like a sore thumb." He did not know what was happening inside the mall when he witnessed the arrest.

The sprawling, three-level mall has more than 135 stores and restaurants, according to the Web site for General Growth Properties, the manager of the mall. It gets 14.5 million visitors every year, according to the Web site.

On Friday night, authorities removed a live grenade from the parking lot of the same mall.

President Bush was in town Wednesday for a fundraiser in Omaha, but left about an hour before the shooting.

Wednesday's shooting was the second mass shooting at a mall this year. In February, nine people were shot, five of them fatally, at Trolley Square mall in Salt Lake City. The gunman, 18-year-old Sulejman Talovic, was shot and killed by police.

This is a developing story. Refresh this page for updates.

The Associated Press contributed to this report.