The gunman who killed five people at Northern Illinois University was identified Friday as 27-year-old Steven Kazmierczak -- described as a promising former student who was "revered" by faculty.
University Police Chief Donald Grady said Kazmierczak was known widely as an "outstanding" student while at NIU.
"We had no indications at all this would be the type of person that would engage in such activity,'' he added.
School websites described Kazmierczak as an award-winning sociology student who led a campus criminal justice group.
Armed with a pump-action shotgun and three handguns, Kazmierczak opened fire in a lecture hall filled with more than 100 students on Thursday afternoon.
Kazmierczak also wounded at least 15 others before shooting himself.
Investigators recovered 48 shell casings and six shotgun shells at the scene, said Grady.
DeKalb County coroner Rusty Miller said Friday that there had been confusion over the death toll and that the gunman killed five people, not six as earlier reported.
"There was a miscommunication," he said.
Kazmierczak graduated from NIU in 2007 and moved on to the graduate school of social work at the University of Illinois in Champaign.
Grady said Kazmierczak left no note and there was no clue as to his motive. Without giving details, Grady added that Kazmierczak had become erratic in the past two weeks after he had stopped taking his medication.
Guns legally bought
Police said on Friday they learned Kazmierczak bought two guns -- a Remington shotgun and a Glock 9mm handgun -- at a Champaign, Ill., gun store on Feb. 8.
On Aug. 6, Kazmierczak bought the other two handguns -- a High Point .380 on Dec. 30 and a Sig Sauer on Aug. 6. -- at the same store.
Kazmierczak had no criminal record. All four of his guns were bought legally from a federally-licensed gun dealer, said Thomas Ahern, spokesperson for the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives.
Police say Kazmierczak carried the shotgun to the crime scene in a guitar case. He carried the three other guns under his coat.
His distraught father, Robert Kazmierczak, spoke briefly to reporters outside his single-story house in Lakeland, Fla.
"Please leave me alone . . . This is a very hard time for me," he said.
Kazmierczak grew up in Elk Grove Village, a Chicago suburb near O'Hare Airport. His mother died in Florida in 2006 at age 58.
One neighbour told The Associated Press that it was "not possible" for Steven Kazmierczak to have committed such an act, adding that "he seemed to be much too nice."
Political reaction
U.S. President George Bush on Friday called the shooting a "tragic situation."
"Obviously, a tragic situation on that campus, and I asked our fellow citizens to offer their blessings," Bush said.
Democratic presidential rivals Barack Obama and Hillary Rodham Clinton, meanwhile, called for a stand on gun violence after Thursday's shooting rampage.
Obama said although he respects the Second Amendment, there is no reason local governments cannot introduce gun safety laws to deal with violence in their communities.
Clinton said the government has to do everything it can in taking "reasonable steps" to keep children safe.
Terrified students
Witnesses said Kazmierczak was dressed in black and was wearing a stocking cap when he emerged from behind a screen on the stage of Cole Hall.
Screams filled the hall as Kazmierczak sprayed bullets into the auditorium.
Survivor James Donahue told ABC News he was shot as he tried to escape from the chaos.
"As soon as I got in the aisle he must have turned towards me and he hit me back in my left shoulder and back of my head."
The 25,000-student campus is located in DeKalb, about 100 kilometres west of Chicago.
With files from the Associated Press
