NEW YORK: In yet another campus shooting in the US, a heavily-armed former student gunned down five students and injured 16 others in a Northern Illinois University lecture hall before turning the gun on himself, shocking the country on Valentine's Day.

The tall, white, skinny assailant, dressed in black, emerged from behind a screen on the stage with two handguns and a shotgun and sprayed bullets on the startled students of the geology class without saying a word, officials and eyewitnesses said. This is the fourth shooting to rock US schools and colleges within a week. On February 8, a woman shot dead two fellow students before committing suicide at Louisiana Technical College.

In Memphis, a 17-year-old allegedly shoot and critically wounded a fellow student on Monday. All of the dead, including four women, in the Valentine's Day shooting were students, John G. Peters, the president of Northern Illinois University, told reporters. Six of the 16 injured were in critical condition. Authorities did not immediately identify the gunman who died of a self-inflicted gunshot wound. His body was found on the stage of the lecture hall along with three weapons two handguns and the shotgun, with ammunition still left in both handguns. Gun magazines were found "all over the floor," Donald Grady, the NIU police chief, said.

"This thing started and ended within a matter of seconds," he said adding they could not ascertain any motive as of now. Shots rang out shortly after 3 PM Central Time inside Cole Hall of the 113-year-old university where 25,000 students, including, 862 foreigners, are enrolled. A student who identified herself as Sheila told WBBM radio that the gunman was holding a "huge gun" and she thought that it was a fake. "He was quiet.

He just stood on the stage in front of everybody and just started shooting," she said. "I saw him holding the gun and it was huge. I thought it was fake and then I realized he was really shooting at people and I got down. I saw a lot of blood." Security around campus was increased in December when police found threats scrawled on a campus bathroom wall that included racial slurs and references to last April's Virginia Tech killings, CNN reported. A heavily armed South Korean student had killed 32 people on his campus at Virginia Tech before committing suicide. One of the threats said "things will change most hastily" in the final days of the semester.

Peters said the motive for the "senseless tragedy" was unknown, but authorities had "no reason to believe" it was related to threats found in December. Illinois Governor Rod Blagojevich declared a state of emergency, which will open the governor's disaster fund to reimburse local government entities. Desiree Smith said she saw fellow students fall down around her as the gunman opened fire. She tried to crawl away thinking she was going to die, then wondered if she should play dead before getting up to run out of the classroom.

Peters said the gunman was enrolled as a graduate student at NIU in the spring of 2007. There are about 162 registered students in the class. Rosie Moroni, a student at the school, she heard shots coming from the classroom which followed by "a lot of people screaming." Then people ran out the doors yelling, "He's got a gun, call 9-1-1," she said. "It was complete chaos ... It's very scary here right now."