By Tom Leonard in New York

Last Updated: 2:38am GMT 15/02/2008

A gunman has opened fire in a packed university lecture hall in Illinois, shooting 18 people and killing four before turning his gun on himself.

	Rescue workers carry a victim out of the university lecture hall where the gunman opened fire

The attacker, described as a tall skinny white young man dressed entirely in black, walked out from behind a screen in a geology class around 3pm, said officials at Northern Illinois University.

The gunman, armed with a shotgun and two handguns, then opened fire before shooting himself on the stage.

Police officials said five people had died, including the gunman. Many victims were shot in the head at the university in DeKalb, 65 miles west of Chicago.

Witnesses said the gunman- said to be aged between 18 and 20 – kicked open a door near the stage in Cole Hall just 10 minutes before the end of the lecture and started shooting with the shotgun without saying a word.

Dispensing with the shotgun, the gunman – who was wearing a black ski cap and black trenchcoat – pulled out a pistol and walked down the aisles firing it into the crowd of terrified students.

Police Chief Donald Grady said the gunman was a student but not at the DeKalb campus.

Kevin McEnery, who was sitting in the fourth row of the lecture, estimated that he let off around 30 shots. He said: “He just kicked the door open and started shooting. I didn’t hear him say anything, just people shouting and screaming to get out.”

Some students dived for cover under their desks while others ran for the exits.

The campus was plunged into panic, as students poured out of the building, many trying to use their mobile phones and others simply praying.

All the injured were taken to the local Kishwaukee Community Hospital which said it had received 17 victims, of whom three or four had head wounds.

The university issued a statement on its website about an hour after the shooting saying that “the immediate danger has passed. The gunman is no longer a threat.”

George Gaynor, a fourth year geography student, who was in Cole Hall when the shooting happened, described the gunman as “a skinny white guy with a stocking cap on”.

He described the scene immediately following the incident as terrifying and chaotic. “Some girl got hit in the eye, a guy got hit in the leg,” he said.

Some witnesses said the gunman shot at random but Edward Robinson, another student, claimed he appeared to target students in one part of the lecture hall. “It was almost like he knew who he wanted to shoot. He knew who and where he wanted to be firing at,” he said.

All classes were cancelled on Thursday night and the 25,000-student campus was closed on Friday.

In April last year, 32 died after a mentally-disturbed and heavily armed student ran amok in the Virginia Tech campus. The incident prompted immediate changes in Virginia law that had allowed the gunman, Seung-Hui Cho, to buy handguns.