MOSCOW, Russia (AP) — Russian officials said an 18-year-old student attacked his vocational school Wednesday in Crimea, going on a rampage that killed 17 students and left more than 40 people wounded before killing himself. One student said the shooting went on for at least 15 minutes.

Russia’s Investigative Committee, the nation’s top investigative agency, said the attacker was caught on security cameras entering Kerch Polytechnic College in the Black Sea city of Kerch and firing at students. It identified him as Vladislav Roslyakov.

Sergei Aksyonov, the regional leader in Crimea, said the fourth-year student at the school had acted alone and killed himself in the school’s library after the attack.

The committee said all the victims died of gunshot wounds.

The statements came after hours of rapidly shifting explanations by Russian officials as to what exactly happened at the school. Officials at first reported a gas explosion, then said an explosive device had ripped through the college canteen during lunchtime in a suspected terrorist attack. Witnesses, however, reported that victims were being killed by a gunman or gunmen.

Reflecting the official confusion, Russian President Vladimir Putin said the victims were killed by an explosion just as the Investigative Committee was announcing they were fatally shot.

Russian news media showed a security camera image of the suspect wearing white T-shirt walking down the school’s stairs with a shotgun.

Russian television said Roslyakov’s mother, a nurse at a local hospital, was helping the wounded, unaware that her son was the suspected attacker. It quoted those who knew Roslyakov as saying he was not very sociable and often put gloomy posts on his social media page.

A sombre-faced Putin deplored the attack as a “tragic event” and offered his condolences to the victims’ families at a news conference in the southern city of Sochi, where he was having talks with Egyptian President Abdel-Fattah el-Sissi. Putin led those present in a moment of silence and some events on his official programme were cancelled.

After the attack, local officials declared a state of emergency on the Black Sea peninsula that Russia annexed from Ukraine. They also beefed up security at a new 19-kilometre (nearly 12-mile) bridge linking the peninsula with Russia, which opened earlier this year. Military units were deployed around the college to help emergency agencies.