At least 17 people, mostly teenagers, were killed and 50 more wounded when a student went on a shooting spree in his high school in Russia-annexed Crimea on Wednesday, Russian authorities said.

Russian investigators identified 18-year-old Vladislav Roslyakov as the attacker, saying he fatally shot himself after the rampage in Kerch, a city in the east of Crimea, which Russia seized from Ukraine four years ago.

Reports had initially described the attack as involving explosives with possibly terrorist motives.

Russian investigators had initially opened a terrorism probe into the attack, but later changed it to murder. โ€œA preliminary examination of the dead shows they suffered from gunshot wounds,โ€ Russiaโ€™s investigative committee said in a statement. โ€œThe majority of them are teenagers,โ€ it added.

But there were conflicting reports about what took place. Russiaโ€™s anti-terrorism committee initially said an explosive device was to blame for the attack on the vocational high school, attended by adolescents between the ages of 15 and 19. It said the bomb had been planted in the cafeteria.

President Vladimir Putin expressed his condolences to the families of victims. โ€œIt is clear that a crime took place. The motives and scenarios of this tragedy are being studied,โ€ he said at a meeting with his Egyptian counterpart Abdel-Fattah el-Sissi in the Black Sea city of Sochi. He then asked for a momentโ€™s silence.

Russian media released a photograph of Roslyakov. With his shorn blonde hair and combination of black pants and a white T-shirt, comparisons were made to the Columbine High School massacre in 1999, when one of the two gunmen wore a similar outfit. Roslyakov is pictured holding an automatic rifle.

The Russian news service Mash described Roslyakov as an introverted loner with a fondness for โ€œmaniacs.โ€ He purchased an automatic rifle and cartridges last week, his classmates are cited as saying.

As the wounded poured into a local clinic, the attackerโ€™s mother, a nurse called Galina Roslyakova, attended to them, Mash reported. She was later called away to meet with investigators.

Russia has relatively strict gun laws, and such shooting massacres are rare. In recent years, there have been several incidents involving students launching attacks with axes, knives and air guns.

The attack is the first fatal attack on territory controlled by Russia since a suicide bomber killed 16 people on the St. Petersburg metro in April last year. No group claimed responsibility for that attack, but Russian security forces said it was the work of an Islamist radical.