At least 17 people were killed and dozens injured at a college in the Black Sea region of Crimea on October 17, 2018. (Source: The Moscow Times)

Eighteen-year-old Vladislav Roslyakov turned up at the college in the city of Kerch on Wednesday afternoon carrying a firearm and then began shooting, investigators said. His body was later found in the college with what they said were self-inflicted gunshot wounds.

There were no immediate clues as to his motive in mounting such an attack, which recalled similar shooting sprees carried out by students in US schools.

Many of the victims from Wednesday's attacks were teenage students who suffered shrapnel and bullet wounds.

Pupils and staff described scenes of mayhem as panicked pupils tried to flee the building. They said the attack had started with an explosion, followed by more blasts, and a hail of gunfire.

Russian President Vladimir Putin, at a meeting in the southern Russian resort of Sochi with his Egyptian counterpart, declared a moment's silence for the victims.

"This is a clearly a crime," he said. "The motives will be carefully investigated."

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.

Crimea was incorporated into Russia in March 2014 following a local referendum. Ukraine says the peninsula was annexed.