DEKALB, Ill. (AP) — A former student dressed in black opened fire Thursday with a shotgun and two handguns from the stage of a Northern Illinois University lecture hall, killing five students and wounding more than a dozen others before committing suicide.

University President John Peters said there were 22 casualties from a "very brief rapid-fire assault" that sent terrified students running for cover. The gunman shot himself on the stage after a rampage that lasted no more than two minutes.

The dead included four females and two males, including the killer, Peters said.

Dan Parmenter, a 20-year-old sophomore from Elmhurst, Ill., was one of those killed, his stepfather, Robert Greer, told the Chicago Tribune.

"I'm not angry," Greer said. "I'm just sad, and I know that right now what I need to do is comfort my wife."

All those killed were students and one of the wounded was the class instructor, Peters said. He said the gunman was a former graduate student in sociology at NIU, but was not currently enrolled. Authorities know of no motive.

"I kept thinking, 'Oh God, he's going to shoot me. Oh God, I'm dead. I'm dead. I'm dead,'" said Desiree Smith, a senior journalism major who was sitting near the back of the auditorium.

Smith said she looked up and saw an unfamiliar man with a "huge rifle" on the stage who began shouting at the teacher and other students. She dropped to the floor, where she saw the face of another female student underneath the seats. She grabbed the girl's leg out of fear.

"We watched each other, not blinking," Smith said. Then, as other students began crawling toward the back exit, she did the same.

"People were crawling on each other, trampling each other," she said. "As I got near the door, I got up and I started running."

Joseph Peterson, the 26-year-old graduate student teaching the geology class, told the Chicago Sun-Times the gunman appeared about 40 feet away from him and "just started firing away." The gunman chased Peterson, who escaped out a door and was later hospitalized with a shoulder wound.

Lauren Carr said she was sitting in the third row of the lecture hall when she saw the gunman walk through a door on the right-hand side of the stage, pointing a gun straight ahead.

"I try to be a good student and sit close to the front and this is what happens," said Carr, a 20-year-old sophomore. "I personally Army-crawled halfway up the aisle ... I said I could get up and run or I could die here."

A student in front of her was bleeding, "but he just kept running," she said. "I heard this girl scream, 'Run, he's reloading the gun.'"

Eighteen victims were brought to nearby Kishwaukee Community Hospital, where one died, according to spokeswoman Theresa Komitas. School officials said four people, including the gunman, died at the lecture hall and two later died at hospitals.

The shooting took place about 3 p.m. and was over in an instant.

"At this point I'm being told it was less than two minutes," campus Police Chief Donald Grady said. "This thing started and ended in a matter of seconds."

Michael Gentile was meeting with two of his students directly beneath the lecture hall when the shootings happened. He could hear the chaos a few feet above his head.

"The shotgun blast must have been so loud," said Gentile, a 27-year-old media studies instructor. "It sounded like something was dropping down the stairs... We had no idea what this was."

Then, shorter, sharper noises he recognized as handgun shots.

"There was a pretty quick succession ... just pow, pow, pow," said Gentile, who didn't leave his office for about 90 minutes. He used a surveillance camera just outside his office to confirm that the people knocking on his door were police.

George Gaynor, a senior geography student, who also was in Cole Hall when the shooting happened, told the student newspaper the Northern Star the shooter was "a skinny white guy with a stocking cap on."

He described a terrifying scene.

"Some girl got hit in the eye, a guy got hit in the leg," Gaynor said outside just minutes after the shooting occurred.

Student Edward Robinson told WLS-TV the gunman appeared to target students in one part of the lecture hall.

"It was almost like he knew who he wanted to shoot," Robinson said. "He knew who and where he wanted to be firing at."

Alan Edrinn, 21, a journalism major, arrived at the scene around 3:30 p.m. after hearing reports of the shooting.

"It was very chaotic," he said. "People were definitely in a panic. I saw some people running. Everyone was on their cell phone. I saw bodies on the sidewalk, it looked like two, people were attending to them," Edrinn said.

"Police were trying to get people back, there were people crying," he added.

The federal Bureau of Alcohol, Tobacco and Firearms sent 15 agents to the scene, according to Thomas Ahern, a spokesman. He said information about the weapons involved would be sent to the ATF's national database in Washington and given urgent priority.

The FBI also was assisting.

All classes were canceled Thursday night and the 25,000-student campus was closed on Friday. Students were urged to call their parents "as soon as possible" and were offered counseling at any residence hall, according to the school Web site.

The school was closed for one day during final exam week in December after campus police found threats, including racial slurs and references to shootings earlier in the year at Virginia Tech, scrawled on a bathroom wall in a dormitory. Police determined after an investigation that there was no imminent threat and the campus was reopened. Peters said he knew of no connection between that incident and Thursday's attack.

The shooting was the fourth at a U.S. school within a week.

On Feb. 8, a woman shot two fellow students to death before committing suicide at Louisiana Technical College in Baton Rouge. In Memphis, Tenn., a 17-year-old is accused of shooting and critically wounding a fellow student Monday during a high school gym class, and the 15-year-old victim of a shooting at an Oxnard, Calif., junior high school has been declared brain dead.

On Facebook, students from Northern Illinois and other universities urged one another to wear "Huskie red" Friday to support NIU students and their families.

"I will wear red with absolute pride tomorrow as I'm sure you all wore your orange and maroon for us," wrote one student at Virginia Tech, where 32 were slaughtered by a suicidal gunman last year. "Know that we are here for you in your time of need as you were for us."