The suspect who gunned down six people in a Northern Illinois University lecture hall before committing suicide was identified Friday as 27-year-old former student Steven Kazmierczak, according to Florida authorities and a source familiar with the investigation.

Polk County, Fla., sheriff’s officials said they were asked to notify the suspect’s father — Robert Kazmierczak of Lakeland, Fla. — of his son’s death.

“His son, Steven, was the shooting suspect at Northern Illinois University and … he was deceased,” said Carrie Rodgers, spokeswoman for the sheriff’s office.

Illinois authorities have not confirmed the suspect’s identity, but it is the younger Kazmierczak, a university source told The Associated Press on condition of anonymity because the identity has not been officially released.

The gunman also wounded 15 people in Thursday’s attack, which sent panicked students fleeing for the exits before he killed himself. The motive of the killer, who graduated from NIU in 2006 and was believed to be a student at the University of Illinois, was still not known.

“There is no note or threat that I know of,” NIU President John Peters said on Friday ABC’s “Good Morning America.” ”By all accounts that we can tell right now (he) was a very good student that the professors thought well of.”

Witnesses said the gunman, dressed in black and wearing a stocking cap, emerged from behind a screen on the stage of 200-seat Cole Hall and opened fire just as the class was about to end around 3 p.m. Officials said 162 students were registered for the class but it was unknown how many were there Thursday.

Allyse Jerome, 19, a sophomore from Schaumburg, said the gunman burst through a stage door and pulled out a gun.

“Honestly, at first everyone thought it was a joke,” Jerome said. Everyone hit the floor, she said. Then she got up and ran, but tripped. She said she felt like “an open target.”

“He could’ve decided to get me,” Jerome said. “I thought for sure he was gonna get me.”

John Giovanni, 20, of Des Plaines said the gunman calmly fired at the greatest concentration of students.

“He was shooting from the hip. He was just shooting,” said Giovanni, who turned and ran so fast that he lost a shoe. “I was running but I was hurtling over people in the fetal position.”

Peters said four people died at the scene, including three students and the gunman. The others died at hospitals. The teacher, a graduate student, was wounded but was expected to recover.

DeKalb County Coroner Dennis J. Miller released the identities of the four victims: Daniel Parmenter, 20, of Westchester; Catalina Garcia, 20, of Cicero; Ryanne Mace, 19, of Carpentersville; and Julianna Gehant, 32, of Meridan.

Another victim, Gayle Dubowski, a 20-year-old sophomore from Carol Stream, died at a Rockford hospital, Winnebago County Coroner Sue Fiduccia said Friday.

The killer had been a graduate student in sociology at Northern Illinois as recently as spring 2007, but was not currently enrolled at the 25,000-student campus, Peters said. He also said the suspect had no record of police contact or an arrest record while attending Northern Illinois, about 65 miles west of Chicago.

The Chicago Tribune, citing two unidentified law enforcement sources, reported Friday that the gunman was a graduate student at the University of Illinois at Urbana-Champaign.

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

“I personally Army-crawled halfway up the aisle,” said Carr, a 20-year-old sophomore. “I said I could get up and run or I could die here.”

She said a student in front of her was bleeding, “but he just kept running.”

“I heard this girl scream, ‘Run, he’s reloading the gun!'”

More than a hundred students cried and hugged as they gathered outside the Phi Kappa Alpha house early Friday to remember Parmenter, the 20-year-old sophomore from Elmhurst, who was one of those killed.

“I’m not angry,” his stepfather, Robert Greer, told the Tribune. “I’m just sad, and I know that right now what I need to do is comfort my wife.”

The 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.