Russian President Vladimir Putin called the deadly shooting and bomb attack by a teenager in Crimea a "result of globalization" and said that adults are failing to offer young people an alternative to an outburst of violence.

Speaking at an international conference of policy experts, Putin yesterday linked the attack to "globalization," drawing parallels to shooting attacks in the U.S., according to the Associated Press. Putin said the fact that teenagers get shotguns and go on a shooting rampage means that adults are "reacting poorly to fast-changing realities."

Several media outlets made a comparison with the 1999 Columbine High School shooting in the U.S., which left 13 people dead. They alleged photos of the Kerch killer circulating on the internet showed him wearing a similar T-shirt to Eric Harris, one of the Columbine killers.

An 18-year-old student went on a rampage at his vocational school in the city of Kerch on Wednesday, killing 20 people and injuring more than 50. The motives of the killer are unclear although top Crimean officials said that authorities suspect he had an accomplice who helped him plot the attack.

The teenager had spoken about taking revenge for bullying, his ex-girlfriend told Russian media yesterday. "He would say that he lost trust in people when his classmates began humiliating him for not being like everyone else," a 15-year-old named as Zlata told the Kremlin-funded RT television of Vladislav Roslyakov, as reported by Agence France-Presse (AFP). "Vladislav was always telling me about his frequent fights with people around him," she said.

Media published details about the killer, who officials say committed suicide at the end of his rampage. According to the Russian daily Kommersant, the teenager "grew up in a rather poor family" with a disabled father. The paper said Roslyakov's mother is a Jehovah's Witness, a Christian organization considered "extremist" and banned in Russia. Russian television reported that his mother works as an orderly at one of the hospitals that treated victims.

Attacks by disaffected teenagers at schools and colleges have hit the headlines recently in Russia. In January, a school student attacked a teacher and fellow students with an axe in Siberia and tried to set fire to the school building. In April, another student stabbed a teacher and a fellow student in the Urals Mountains and then set fire to a classroom.