“We were dealing with a disturbed individual,” said NIU President John Peters.

The name of the shooter was officially announced at a 9 a.m. NIU press conference: Stephen P. Kazmierczak, 27, of Elk Grove. Kazmierczak had been a graduate student at NIU in Spring 2007, and was enrolled this semester at the University of Illinois at Urbana-Champaign.

Forty-eight shell casings from Kazmierczak’s three handgums and six shells from his shotgun were recovered in the Cole Hall auditorium, said Kevin Cronin of the US Bureau of Alcohol, Tobacco and Firearms agent.

The shooter had finished shooting before police arrived on scene, said University Police Chief Donald Grady.

Grady said Kazmierczak reloaded the shotgun after shooting three rounds.

Kazmierczak had legally purchased two of the firearms, a Glock 9 mm and a Remington 12-gauge shotgun Model 870, on Feb. 9 from an unidentified gun dealer in Champaign, Cronin said. Kazmierczak carried two additional handguns: a Sig Sauer 9 mm pistol and a Hi-Point .380 pistol. Cronin said the ATF was trying to track the weapons’ origins.

All of the firearms were purchased legally from the same store in Champaign-Urbana, said Thomas Ahern, ATF spokesperson for the Chicago Field Division.

Two firearms, the shotgun and one of the semi-automatic handguns, were purchased on Feb 9; officials are still unsure when the two other firearms were purchased, Ahern said.

The exact number of shots fired is still under investigation, Ahern said.

“Most semi-automatics have 10 to 12 rounds of ammo per gun,” Ahern said. “The shotgun would hold five rounds at a time.”

“As we understand, [Kazmierczak] was seen outside the building, but [witnesses] did not see anyone with the weapons,” Grady said.

Kazmierczak carried the shotgun in a guitar case into the auditorium.

Grady said Kazmierczak had been on medication, but he had stopped taking his medication recently and had begun acting “erratic in the last few weeks.” While at NIU, there were “no red flags” and Kazmierczak was “revered by staff,” Grady said.

Grady was unable to comment on which medication Kazmierczak was on or for what condition he was taking it.

Additionally, no notes have been found that would indicate a motive for the attack and there was also no obvious relationship to anyone in the class at the time, Grady said.

Kazmierczak’s car was parked “not far” the building and it is still being inventoried Grady.

Two police units responded within a minute of the call and eight additional units were in the area shortly after that, Grady said.

Kazmierczak graduated from Elk Grove High School.

The gunman’s mental state and his ability to purchase firearms has come into question.

“Unless there was something on his record that he had been mentally ill that was stopping him” from buying a gun, Kazmierczak would have been legally allowed to purchase firearms, Ahern said.

Eric Rood and Caitlin Mullen contributed to this story.