BLACKSBURG, Va. — "He never said a word the whole time. I've never seen a straighter face."

That is how Trey Perkins, a senior at Virginia Tech, recalled the gunman who burst into his German class here on Monday, pointed a handgun at each student and pulled the trigger.

In the end, Perkins, who crouched behind desks in the back of the classroom, managed to escape uninjured. But he was one of the few. The classroom on the second floor of Norris Hall appears to be where the gunman, a 23-year-old South Korean native identified as Cho Seung-Hui, exacted his greatest toll — as many as a dozen people.

It was a scene of utter terror and panic inside Room 207, with students trying to escape out windows or cowering under desks as the gunman, dressed in a black leather jacket and wearing a maroon baseball cap, fired, reloaded and then fired again.

At one point, the gunman left inexplicably, only to return, with students wedging themselves against the door to block his entry. "The guy tried to come back in, and we were able to hold him off," Perkins said.

Before the initial attack, the class of roughly 20 students had been gathered for about an hour as the professor, Jamie Bishop, delivered a lesson on the rudiments of German, witnesses said.

At that point, there was nothing out of the ordinary, except for when someone opened the door and began peeking into the room. The class assumed that it was a lost student looking for a classroom.

But about 10 minutes later, the door swung open, the shooter entered and took direct aim at Bishop, a popular 35-year-old professor known for riding his bicycle around the campus.

Cho then quickly turned on the horrified students — who hit the ground and pushed over desks to shield themselves, starting with those seated in the front rows of the classroom, the witnesses said.

"We got down, tried to get on the ground," Perkins, a 20-year-old mechanical engineering student from Yorktown, Va., said in an interview. "There were a couple of screams, but for the most part it was eerily silent, other than the gunfire."

Derek O'Dell, a 20-year-old biology student who was in the classroom, told The Roanoke Times: "He was very quick in reloading, so he looked like he'd been trained. No one was really moving."

Then, for reasons that are still unclear, Cho suddenly stopped firing and left the room, as the students lay bleeding on the floor.

Perkins said that, at the time, he was fearful that Cho was still nearby and might return if he thought anyone in the classroom remained alive.