At least 10 people have been killed and dozens more wounded in an explosion at a college in Russian-annexed Crimea.
Officials said an “unidentified explosive device” detonated at the technical college in Kerch, where Russia has built a bridge between the peninsula and Russia.
Initial reports had suggested that the blast was some sort of gas explosion.
But a Russian national guard official said the incident was a deliberate “terrorist act”.
Sergei Melikov told Tass news agency the explosion had been caused by an improvised explosive device.
A Kremlin spokesman had also said that a deliberate attack was now being investigated as a possibility.
A local official said most of the blast victims were students of the technical college, which is a vocational school for teenagers.
The director of the college, who had not been at the scene at the time of the attack, told Russian media that unknown armed men had broken into the building. She compared it to the school siege of Beslan in 2004, during which about 330 people died.
“There were lots of corpses, corpses of kids, a real terrorist attack,” she said.