At 9.15am in Room 207, 15 college students prepared to begin a German class.

Cho Seung Hui poked his head around the door, disappeared for a few seconds, then came back for another look. He took five steps inside the room, raised a Glock 9mm pistol and shot Professor James Bishop through the head.

Cho, wearing jeans, a tan shirt, a black ammunition belt and a backpack, then turned his gun to the front row of students. He shot each one several times, sending spurts of blood on to the floor and walls as he continued his massacre.

“He didn’t say a thing,” said Trey Perkins, one of only three Virginia Tech students to walk out of the second-floor room alive. “I dived to the ground and turned some desks over. He stopped to reload twice. The shots seemed to last for ever.”

As the bodies piled up in Room 207, a classroom in the university’s Norris Hall building, Erin Sheehan dived under the corpses and played dead, as Cho — “dressed almost like a Boy Scout” — continued to shoot. “I saw bullets hit people’s bodies. There was blood everywhere.”

Her clothes, she said, were soaked through with her fellow students’ blood.

The gunman then left, but returned two minutes later. By then, Ms Sheehan, Mr Perkins and another student — the only ones not shot — had barricaded themselves in with their feet. One injured student lay whimpering. Another vomited. Mr Perkins, 20, used a sweat-shirt to cover the face of one young woman who had been shot in the mouth.

Cho, whose backpack contained a second weapon, a .22 pistol, fired repeatedly through the door. He then moved down the corridor to Room 204 in search of more victims.

“It is a horrific crime scene,” Colonel Steve Flaherty, of Virginia police, said. The 32 bodies “were found in at least four classrooms and a stairwell”.

He added: “What went on during this incident caused tremendous chaos and panic. There are personal effects strewn about the second floor.”

Ten students had already jumped out of the window in Room 204 when Cho entered the engineering class of Professor Liviu Librescu, a Holocaust survivor, who tried to shield his students by blocking Cho’s way.

Richard Mallalieu, landing on the grass below, said that he heard about 40 shots — a steady “pop, pop, pop” in the room he had just left — and multiple screams. Professor Librescu was killed, on Holocaust Memorial Day.

Tina Harrison, in a classroom above, said: “I heard horrible, horrible screams of agony. He was coming up the stairwell. We heard gunshots coming closer and closer and we could smell the gunsmoke. There were so many gunshots — at least 100 — and screams. It was hell.”

Tyler Henderson, a 20-year-old student who was in a class at Shanks Hall, diagonally opposite Norris Hall, said: “We had no idea what was going on. They kept us in our classroom but we could see it was chaos. People were running around, people were jumping out of windows.”

Opposite Room 204, Zach Petkewicz peered out of his classroom. “I saw a gunman come out, his gun pointed down.” Mr Petkewicz, 20, pushed desks behind the door, and lay behind them.

“He tried to force his way in, he got the door about six inches open. He shot twice through the door. I heard the clip drop, heard him reload. I thought he was coming back in, but he carried on firing down the corridor.”

Gene Cole, 52, a cleaner in Norris Hall, went up to the second floor and saw a teenage girl lying wounded in the corridor. “I bent over her to get a closer look when this guy came out of the classroom and started shooting at me. It was an automatic.

“He unloaded five bullets at me. I took off running down the steps. I could feel the bullets going past my head.”

A few moments later, Cho, who was almost 6ft, heard armed police approaching fast. He shot himself in the face and was found amid the bodies of his victims.

Cho, whose parents run a dry cleaners in nearby Centreville, was a “lawful resident” in the US and one step from becoming a naturalised citizen. He began his massacre at 7.15am — two hours before most of his victims were to die — half a mile across Virginia Tech’s vast 2,600-acre campus in Ambler Johnston Hall, a mixed dormitory building holding 895 students.

With his two pistols, both of which had the serial numbers filed off, he entered one dormitory and shot at pointblank range Emily Hilscher, a first-year student.

Police are investigating whether he was romantically linked to Ms Hilscher or had been rejected by her. Cho also shot and killed Ryan “Stack” Clark, a final-year student who had gone to Ms Hilscher’s aid.

He then returned to Harper Hall, his own hall of residence and rearmed, before walking across campus to murder his 30 other victims in Norris Hall, and wound 15. Seven were in a critical condition last night.

“There wasn’t a shooting victim that didn’t have less than three bullet wounds,” said Dr Joseph Cacioppo, of Montgomery Regional Hospital.

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