An explosive device has killed at least 18 people and injured 40 others at a vocational college in Crimea in what Russian officials called a possible terrorist attack.

Russian news media reported that some of the victims died in an attack by an unidentified gunman or gunmen, and the head of Crimea, Sergei Aksyonov, said the attacker was a fourth-year student at the school who killed himself after the attack.

Russia’s National Anti-Terrorism Committee said the blast at the college in the city of Kerch in eastern Crimea was caused by an unidentified explosive device.

Emergency officials had initially said the blast was caused by a gas explosion.

Emergency services at the scene
Emergency services at the scene (Kerch FM News/AP)

Sergei Melikov, a deputy chief of the Russian National Guard, said the explosive device was homemade.

Russia’s Investigative Committee, the nation’s top investigative agency, said the device went off in the college canteen and was rigged with shrapnel.

Committee spokeswoman Svetlana Petrenko said 13 people were killed and about 50 injured, most of them students.

Explosives experts are inspecting the college for other possible bombs, according to Anti-Terrorism Committee spokesman Andrei Przhezdomsky.

Russian President Vladimir Putin’s spokesman, Dmitry Peskov, told reporters that officials are looking into a possible terrorist attack.

He said Mr Putin has instructed investigators and intelligence agencies to conduct a thorough probe and offered condolences to the families of the victims.

Olga Grebennikova, director of the college, told KerchNet TV that men armed with automatic rifles burst into the college and “killed everyone they saw”. She said students and staff were among victims.

The Komsomolskaya Pravda newspaper quoted student Semyon Gavrilov, who said he fell asleep during a lecture and woke up to the sound of shooting. He said he looked out and saw a young man with a rifle shooting at people.

“I locked the door, hoping he wouldn’t hear me,” the paper quoted him as saying.

He said police arrived about 10 minutes later to evacuate the college and he saw dead bodies on the floor and charred walls.

Mr Aksyonov and Russian health minister Veronika Skvortsova headed to the area to co-ordinate assistance to the injured. Military units were deployed around the college.

Russia annexed Crimea from Ukraine in 2014, a move that triggered Western sanctions.

Moscow has also supported separatists fighting the Ukrainian government in eastern Ukraine, a conflict that has left at least 10,000 people dead since 2014.