Blacksburg, Va. ? A gunman opened fire in a dorm and classroom at Virginia Tech on Monday, killing at least 30 people in the deadliest shooting rampage in U.S. history, government officials told The Associated Press. The gunman was killed, bringing to death toll to 32, but it was unclear if he was shot by police or took his own life.

“Today the university was struck with a tragedy that we consider of monumental proportions,” said Virginia Tech president Charles Steger. “The university is shocked and indeed horrified.”

The name of the gunman was not immediately released, and investigators offered no motive for the attack. It was not clear if the gunman was a student.

The shootings spread panic and confusion on campus, with witnesses reporting students jumping out the windows of a classroom building to escape the gunfire. SWAT team members with helmets, flak jackets and assault rifles swarmed over the campus. Students and faculty members carried out some of the wounded themselves, without waiting for ambulances to arrive.

The bloodbath took place at opposite sides of the 2,600-acre campus, beginning at about 7:15 a.m. at West Ambler Johnston, a coed dormitory that houses 895 people, and continuing at least two hours later at Norris Hall, an engineering building about a half-mile away, authorities said.

Police said they were still investigating the shooting at the dorm when they got word of gunfire at the classroom building.

After the first shots were fired, students were warned to stay indoors and away from the windows. But some students said they thought the precautions had been lifted by the time the second burst of gunfire was heard, and some bitterly questioned why the gunman was able to strike a second time, two hours after the bloodshed began.

FBI spokesman Richard Kolko in Washington said there was no evidence to suggest it was a terrorist attack, “but all avenues will be explored.”