MOSCOW — A Russian official says the country's top domestic security agency has thwarted a series of attacks on schools in the wake of last month's shooting-and-bomb attack by a teenager on a school in Crimea.

An 18-year-old student went on a rampage at his vocational school in the city of Kerch on Oct. 17, killing 20 and injuring more than 50 before killing himself. His motives remained unclear, but Russian President Vladimir Putin has drawn parallels to shooting attacks in the U.S.

Sergei Yegorov, a deputy department chief at the Federal Security Service (FSB), told lawmakers in remarks carried by Russian news agencies that the agency prevented "a whole series of attacks on schools." He didn't elaborate.

Asked if any of those attempts were linked to international terrorism, Yegorov said no.