Russia’s Investigative Committee, the state body that investigates major crimes, identified 18-year-old student Vladislav Roslyakov as the chief suspect in the attack, adding that he committed suicide after he went on a shooting spree in the vocational college in the Crimean port city of Kerch on Wednesday.
Russian officials initially said they were investigating the possibility that it was terrorism.
However, the Investigative Committee said that it was re-classifying the case from terrorism to mass murder.
Pupils and staff said the attack had started with an explosion, followed by more blasts, and a hail of gunfire.
Russia’s National Anti-terrorism Committee said that there could have been more than one attacker, adding that a search was under way for other possible participants.
According to the security body, an initial examination of the bodies at the site of the attack showed that victims had died of gunshot wounds.
Olga Grebennikova, the college’s director, described a scene of bloodshed at the college whose pupils are mostly teenagers, saying, “There are bodies everywhere, children’s bodies everywhere. It was a real act of terrorism. They burst in five or 10 minutes after I’d left. They blew up everything in the hall, glass was flying.”
“They then ran about throwing some kind of explosives around, and then ran around the second floor with guns, opened the office doors, and killed anyone they could find,” Grebennikova was quoted by Crimean media outlets as saying.
Russia’s Defense Minister Sergei Shoigu said the military was deploying forces and aids to help the victims.
Russian President Vladimir Putin said that investigators were trying to establish the motive for the deadly attack.
“This is a clearly a crime,” he said at a joint press conference with his Egyptian counterpart Abdel Fattah el-Sisi in the southern Russian resort of Sochi, adding, “The motives will be carefully investigated.”
Crimea, then territory of Ukraine, voted in a referendum to join Russia on March 17, 2014. In the referendum, which was held a month after the overthrow of the then-president Viktor Yanukovych, 96.8 percent of participants voted in favor of unification with Russia.