A police officer guards the yard of the technical college in Kerch, Crimea, Russia on Thursday, where a student shot and killed at least 19 people on Wednesday. (Photo: AFP)

Russian investigators on Thursday rushed to establish the motives of a teenage gunman who opened fire in a Crimean technical college leaving at least 19 people dead and dozens injured, with the press dubbing the rampage "Russia's Columbine." 

In the absence of an official version, speculation mounted on social media about what pushed 18-year-old student Vladislav Roslyakov to open fire on his fellow students.

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 TV reported that his mother works as an orderly at one of the hospitals that treated victims.

Several media outlets made a comparison with the 1999 Columbine High School shooting in the US, 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. 

The gunman "moved from room to room and, like an experienced special forces fighter, first threw a home-made grenade before going to shoot people," Kommersant wrote.

City authorities said 19 people were killed - 14 of them students and six under the age of 18 - in the latest death toll on Thursday. More than 40 people were injured.

Crimean leader Sergei Aksyonov said late on Wednesday that 12 people were in an extremely serious condition.

AFP journalists in Kerch, a city on the Crimean peninsula, saw the college cordoned off by Russia's National Guard, the army and the police.