The 16-year-old tells the newspaper Expressen how he saw a schoolmate being attacked in the school's student hall.
He was badly stabbed in both the arm and back, he tells the newspaper.
After the attack, everyone fled in different directions, Fredric Ericson says.
Everyone panicked. We ran out of there. We just ran for our lives.
When he discovered the injured boy, he turned around in his epa tractor and drove the bleeding boy to the hospital in Fagersta.
According to Fredrik Ericson, the perpetrator at Brinell School was masked, with an old-fashioned war helmet on his head and a black balaclava pulled over the lower part of his face.
I was completely shaken. And I still don't think I've taken in exactly what happened. No, it's terrible, he tells Expressen.
Fredrik Ericson's actions are praised by Prime Minister Ulf Kristersson. In a post on Instagram, he writes that "many of us are grateful today for Fredrik's quick and courageous actions in a very difficult situation."
A 17-year-old girl was killed and two boys were seriously injured in the school attack in Fagersta. The suspected perpetrator - a high school student - is in custody, suspected of murder and attempted murder.
