DEKALB - The man who gunned down five people at Northern Illinois University in a suicidal rampage had recently "become erratic'' after halting his medication and carried a shotgun to campus inside a guitar case, police said Friday.

The man, 27-year-old former student Steven Kazmierczak, also wielded three handguns during Thursday's ambush attack inside a lecture hall.

Two of the weapons - the pump-action Remington shotgun and a Glock 9mm handgun - were purchased legally less than a week ago, on Feb. 9, authorities said. They were purchased in Champaign, where Kazmierczak was enrolled at the University of Illinois; authorities would not release the name of the store.

The other two guns were also legally purchased at the Champaign store - a High Point 380 pistol on Dec. 30, 2007, and a Sig Sauer pistol on Aug. 6, 2007, according to Tom Ahern, a spokesman for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives.

Kazmierczak had a valid Firearm Owner's Identification Card, which is required for all Illinois residents who buy or possess firearms, authorities said.

Campus Police Chief Donald Grady said investigators recovered 48 shell casings and six shotgun shells following the attack in Cole Hall. The gunman paused to reload the shotgun after opening fire on a crowd of terrified students in a geology class, sending them running and crawling toward the exits. He shot himself to death on the stage of the hall. Sixteen people were injured.

"Yesterday's shooting was a tragic, senseless and horrific event,'' Gov. Rod Blagojevich said during a news conference on the NIU campus. "We will work to understand the motive of the assailant. If there is a way this tragedy could have been anticipated or stopped beforehand, we will find it.''

Kazmierczak, whose first name was earlier listed as Steven, was taking some kind of medication, Grady said.

"He had stopped taking medication and become somewhat erratic in the last couple of weeks,'' Grady said, declining to name the drug or provide other details.

Correcting information his office released earlier, DeKalb County Coroner Dennis J. Miller said five students, not six, were killed in the rampage, in addition to the gunman. Miller said the higher victim total was the result of confusion over the fate of a patient taken to another county for treatment.

"There was a miscommunication. There are 6 total fatalities,'' Miller said.

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

The elder Kazmierczak briefly came out of his house Friday morning to talk to reporters.

"Please leave me alone. … This is a very hard time for me,'' he said as he threw his arms up and wept. He declined further comment about his son and then went back inside his house, saying he was diabetic.

The motive of the killer, who graduated from NIU in 2006 but was a student there as recently as last year, was still not known. Grady said Kazmierczak was an "outstanding'' student while at NIU and authorities were still trying to determine why he would kill. There was no known suicide note.

"We were dealing with a disturbed individual who intended to do harm on this campus,'' NIU President John Peters said.

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.

The DeKalb County coroner's office 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 Meriden.

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

The killer had been a graduate student in sociology at Northern Illinois as recently as spring 2007, Peters said. He also said the suspect had no record of police contact or an arrest record while attending Northern Illinois, a campus with 25,000 students about 65 miles west of Chicago.

The gunman was a student at the University of Illinois in Urbana-Champaign, Chancellor Richard Herman said.

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 Pi Kappa Alpha house early Friday to remember Parmenter, a sophomore who was one of those killed.

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.

Associated Press writers Don Babwin, Ashley M. Heher, Carla K. Johnson, Tamara Starks, Mike Robinson and Anthony McCartney contributed to this report.

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List of recent deadly campus shootings

Fatal shootings at U.S. colleges or universities in recent years:

Feb. 14, 2008: Stephen Kazmierczak, a 27-year-old former student opens fire in a lecture hall at Northern Illinois University in DeKalb, killing five people. He then commits suicide.

Feb. 8, 2008: Latina Williams, 23, opens fire during an emergency medical technology class at Louisiana Technical College in Baton Rouge, killing Karsheika Graves and Taneshia Butler. She then kills herself.

Dec. 13, 2007: Two Ph.D. students from India are found shot to death in a home invasion at an apartment on the campus of Louisiana State University in Baton Rouge.

Oct. 1, 2007: University of Memphis football player Taylor Bradford, 21, who had been rumored to have won more than $3,000 at a casino, is fatally shot on campus in a botched robbery. Four men are later charged, including one student.

Sept. 21, 2007: Two students are wounded at a late-night shooting at a campus dining hall at Delaware State University in Dover. Shalita K. Middleton, 17, dies Oct. 23 from her injuries. A student is charged in the shooting.

April 16, 2007: Cho Seung-Hui, 23, fatally shoots 32 people in a dorm and a classroom at Virginia Tech in Blacksburg, then kills himself in the deadliest mass shooting in modern U.S. history.

April 2, 2007: A 26-year-old researcher at the University of Washington in Seattle is shot to death in her office by her ex-boyfriend. Jonathan Rowan, 41, then kills himself.

Sept. 2, 2006: Douglas W. Pennington, 49, kills himself and his two sons, Logan P. Pennington, 26, and Benjamin M. Pennington, 24, during a visit to the campus of Shepherd University in Shepherdstown, W.Va.

May 9, 2003: A 62-year-old man with two handguns and a bulletproof vest fires hundreds of rounds during a seven-hour shooting spree and standoff at a Case Western Reserve University building in Cleveland. One student is killed and two others are wounded. Biswanath Halder, who authorities say was upset because he believed a student hacked into his Web site, is eventually sentenced to life in prison.

Oct. 28, 2002: Failing student and Gulf War veteran Robert Flores, 40, walks into an instructor's office at the University of Arizona Nursing College in Tucson and fatally shoots her. A few minutes later, armed with five guns, he enters one of his nursing classrooms and kills two more of his instructors before fatally shooting himself.

Jan. 16, 2002: Graduate student Peter Odighizuwa, 42, recently dismissed from Virginia's Appalachian School of Law in Grundy, returns to campus and kills the dean, a professor and a student before being tackled by students. Odighizuwa is serving six life sentences after pleading guilty.

May 17, 2001: Donald Cowan, 55, fatally shoots assistant music professor James Holloway at a dorm at Pacific Lutheran University in Parkland, Wash., then turns the gun on himself. He leaves a 16-page suicide note expressing anger at a colleague of Holloway's whom he dated briefly as a teenager.

Aug. 28, 2000: James Easton Kelly, 36, a University of Arkansas graduate student recently dropped from a doctoral program after a decade of study and John Locke, 67, the English professor overseeing his coursework, are shot to death in an apparent murder-suicide by Kelly.

June 28, 2000: Medical resident Dr. Jian Chen kills his supervisor and then himself in his supervisor's office at the University of Washington in Seattle. Faculty say Chen, 42, was upset he'd be forced to return to China because of his academic shortcomings.

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NIU facts

Enrollment: 25,000.

Areas of study: Undergraduates can earn degrees in 55 majors from seven schools: business; education; engineering and engineering technology; health and human sciences; law; liberal arts and sciences and visual and performing arts.

President: John Peters has led the school since 2000. He received his Ph.D. in political science from the University of Illinois at Urbana-Champaign.

History: School opened in 1899 as the Northern Illinois State Normal School to educate teachers; it became a university in 1957.

Location: DeKalb, about 65 miles west of downtown Chicago. Outreach centers are in Hoffman Estates, Naperville, Rockford and Oregon, Ill.