The police and Northern Illinois University authorities are trying to find out what drove former student Stephen Kazmierczak to go on a killing spree at the varsity campus.
No suicide note has been found but authorities said that Kazmeirczak became erratic after halting his medication and carried a shotgun to campus inside a guitar case.
Kazmierczak shot dead five students, mostly women, and injured 23 others in Northern Illinois University before turning the weapon on himself on the Valentine's Day, but no Indian casualty has been reported.
A senior Indian Embassy official told PTI that both the Mission in Washington and the Consulate in Chicago were following the tragic incident closely. "At this time, there have been no reports of any Indian students killed or seriously injured," the official said.
Kazmierczak was also wielding three handguns during Thursday's ambush inside a lecture hall on the university campus, some 65 miles outside of Chicago.
The authorities have said that two of the weapons -- the pump-action Remington shotgun and a Glock 9mm handgun -- were purchased legally less than a week ago in Champaign, where Kazmierczak was enrolled at the University of Illinois.
A spokesman for the Federal Bureau of Alcohol, Tobacco and Firearms said the other two guns were also traced to the Champaign gun shop, but the ATF was still determining when the suicidal killer picked them up.
Besides the ATF, the Federal Bureau of Investigation is also involved in the investigation. After a meeting with Republican leaders on Friday morning, President George W Bush spoke briefly about the tragic incident.
"This morning I spoke to the president of Northern Illinois University. I told the president that a lot of folks today would be praying for the families of the victims and for the Northern Illinois University community.
It is obviously a tragic situation on that campus, and I ask our fellow citizens to offer their blessings -- blessings of comfort and blessings of strength," Bush said.
Kazmierczak had a valid Firearm Owner's Identification Card, which is required for all Illinois residents who buy or possess firearms, authorities said. A graduate in Sociology at NIU, Kazmierczak reportedly had no record of police contact or arrest while attending the University campus.
Kazmierczak was a student at the University of Illinois in Urbana-Champaign, which is 140 miles south of Chicago.
The NIU campus was shut down for a day during the 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.
However, the authorities determined that there was no imminent threat and the campus was re-opened.