The death toll of the massacre in Sweden: 11 dead

The student managed to film the attacker from outside. The video shows a man dressed in dark clothes, armed, moving inside the building, Aftonbladet.se reports.

"I think he had two long barrels, one on his back and one in his hands," the student said.

He said that he came early to class and was waiting in the corridor when he heard the first shots.

"At first I thought someone had dropped a chair or something. But when the gunshots continued, I realized it was gunfire and ran towards the main door. I don't know what would have happened if I hadn't taken one of my headphones out of my ear," he said.

As he ran away, he turned around and saw the attacker clearly, as well as the panic that gripped the people around him.

"I saw people falling over each other, trying to get out in a panic. It was terrible."

The footage also shows scenes where some people move calmly and seem oblivious to the danger.

"The school is big, and some people didn't realize it was a shooting. I saw a woman between me and the attacker and tried to shout to her. Then I ran and heard the shots," he added.

When he came out, the student witnessed gruesome scenes as the injured students were carried out and placed in private cars to be taken to the hospital.

Two other students, Omar (18) and Nahom (19), recounted their experience of being locked in the classroom.

"We were sitting in the workshop when our principal came running. Our teacher told us that no one was allowed to go out, and that's when we turned off the lights," Omar said.

When they were finally allowed to go out, they were relieved.

"We're just happy to go home to be with our family. At first I thought it was a fire or something. Then we heard gunshots – it was a shock," added Nahom.