BLACKSBURG, Va. – A gunman massacred 32 people at Virginia Tech in the deadliest shooting rampage in modern U.S. history Monday, cutting down his victims in two attacks two hours apart before the university could grasp what was happening and warn students.

The bloodbath ended with the gunman committing suicide, bringing the death toll to 33 and stamping the campus in the picturesque Blue Ridge Mountains with unspeakable tragedy, perhaps forever.

Investigators gave no motive for the attack. The gunman’s name was not immediately released, and it was not known whether he was a student.

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

But he was also faced with difficult questions about the university’s handling of the emergency and whether it did enough to warn students and protect them after the first burst of gunfire. Some students bitterly complained they got no warning from the university until an e-mail that arrived more than two hours after the first shots rang out.

Wielding two handguns and carrying multiple clips of ammunition, the killer opened fire about 7:15 a.m. on the fourth floor of West Ambler Johnston, a high-rise coed dormitory, then stormed Norris Hall, a classroom building a half-mile away on the other side of the 2,600-acre campus. Some of the doors at Norris Hall were found chained from the inside, apparently by the gunman.

Two people died in a dorm room, and 31 others were killed in Norris Hall, including the gunman, who put a bullet in his head. At least 15 people were hurt, some seriously. Students jumped from windows in panic.

Alec Calhoun, a 20-year-old junior, said he was in a 9:05 a.m. mechanics class when he and classmates heard a thunderous sound from the classroom next door – “what sounded like an enormous hammer.”

Screams followed an instant later, and the banging continued. When students realized the sounds were gunshots, Calhoun said, he started flipping over desks for hiding places. Others dashed to the windows of the second-floor classroom, kicking out the screens and jumping from the ledge of Room 204, he said.

“I must’ve been the eighth or ninth person who jumped, and I think I was the last,” said Calhoun, of Waynesboro, Va. He landed in a bush and ran.

Calhoun said that the two students behind him were shot, but that he believed they survived. Just before he climbed out the window, Calhoun said, he turned to look at the professor, who had stayed behind, perhaps to block the door.

The instructor was killed, he said.

At an evening news conference, Police Chief Wendell Flinchum refused to dismiss the possibility that a co-conspirator or second shooter was involved. He said police had interviewed a male who was a “person of interest” in the dorm shooting who knew one of the victims, but he declined to give details.

“I’m not saying there’s a gunman on the loose,” Flinchum said.

After the shootings, all campus entrances were closed, and classes were canceled through Tuesday. The university set up a spot for families to reunite with their children. It also made counselors available and planned an assembly Tuesday.

“I knew when the number was so large that I would know at least one person on that list,” said Gregory Walton, a 25-year-old who graduated last year. “I don’t want to look at that list. I don’t want to.

“It’s just, it’s going to be horrible, and it’s going to get worse before it gets better.”