MOSCOW — A gunman attacked his fellow students at a technical college on the Crimean peninsula on Wednesday, killing at least 19 people and wounding dozens of others, the Russian authorities said.

The gunman, who also detonated an explosive device, was found dead, apparently a suicide.

The assault at Kerch Polytechnic College was initially investigated as a possible terrorist attack. But officials quickly reclassified it as murder after learning that the gunman, Vladislav I. Roslyakov, 18, was a fourth-year student at the college.

There were no immediate reports of a possible motive, though a friend of Mr. Roslyakov said he was a loner who had expressed an interest in the 1999 school shooting in Columbine, Colo., where 12 students and a teacher were killed.

Mr. Roslyakov’s body was found with a gunshot wound in a room at the college, Russia’s Investigative Committee said in a statement, bringing the overall toll to 20 dead. That represented the greatest loss of life in school violence in Russia since the Beslan terror attack of September 2004, in which 333 people died, many of them children, and 531 were hospitalized.