The director of the school, Olga Grebennikova, described the scene that she encountered when she entered the college building after the attack.
"There are bodies everywhere, children's bodies everywhere. It was a real act of terrorism. They burst in five or 10 minutes after I'd left. They blew up everything in the hall, glass was flying," Grebennikova told Crimean media outlets.
"They then ran about throwing some kind of explosives around, and then ran around the second floor with guns, opened the office doors, and killed anyone they could find."
Soon after the attack, Russian officials said they were investigating the possibility that it was terrorism. Troops with armoured personnel carriers were sent to the scene. Local parents were told to collect their children from the city's schools and kindergartens for their safety.
However, the Investigative Committee, the state body that investigates major crimes, said later that it was re-classifying the case from terrorism to mass murder.
Officials had previously given the death toll as 18, but the Committee revised that to 17 killed. An employee at Kerch's hospital said dozens of people were being treated for their injuries in the emergency room and in the operating theatre.
Anastasia Yenshina, a 15-year-old student at the college, said she was in a toilet on the ground floor of the building with some friends when she heard the sound of an explosion.
"I came out and there was dust and smoke, I couldn't understand, I'd been deafened," she told Reuters. "Everyone started running. I did not know what to do. Then they told us to leave the building through the gymnasium."
"Everyone ran there... I saw a girl lying there. There was a child who was being helped to walk because he could not move on his own. The wall was covered in blood. Then everyone started to climb over the fence, and we could still hear explosions. Everyone was scared. People were crying."