"We have one individual that obviously had some problems. He came to our campus and actually engaged in a serious act of violence," says NIU Police Chief Donald Grady.
Now that Stephen Kazmierczak has been identified as the shooter, the task turns to finding out what made him kill five people and himself.
"We have found no notes at this time, so we have no idea what the motive was, we're still working on that," says Chief Grady.
Grady says there's no indication the shooter knew anyone in the classroom where he opened fire, using three handguns and a shotgun.
"I can't tell you exactly how many shots he fired but I can tell you that we found 48 casings and six shotgun shells that were expended," says Grady.
A representative with the bureau of Alcohol, Tobacco and Firearms said Kazmierczak bought two of the guns legally from a dealer in Champaign just six days ago.
School administrators and police are emphasizing the quick response time and they insist there's nothing they could have done beforehand to prevent this tragedy."
"The staff did everything, everything possible to avoid future tragedies as we had seen at Virginia Tech. I can assure you that the plan was not something put on a shelf, but truly a plan that had been put into action," says Cherilyn Murer, Chair of the NIU Board of Trustees.
"It's an unfortunate set of circumstances, that no one could possibly have predicted, nor could they have been more responsive in getting the event to stop," adds Chief Grady.
Police found Kazmierczak's car near the scene of the crime. It's being inventoried right now. Police say the shooter concealed the handguns under his clothes and carried the shotgun in the building in a guitar case.
Law enforcement officials say all the guns were purchased legally. Kazmierczak passed six background checks, but we only know of four weapons he bought legally.
In a strange twist, Kazmierczak and the Virginia Tech shooter both bought items from the same internet gun dealer. The Green Bay based web site sold a gun holster to Kazmierczak as well as two magazines, each holding up to 33 bullets. That web site also sold a handgun to Cho Sun Hui, the man who killed 32 people at Virginia Tech last April.
Police say Kazmierczak had been taking medication, but went off it recently and had been acting "erratically." Police will not say what the medication was for.