An operation against gunmen who attacked churches and synagogues in Russia's North Caucasus region of Dagestan, killing several people, is over, the country's national agency in charge of fighting terrorism said on Monday. 

"Following the neutralization of the threats to the lives and health of citizens, it was decided to end the anti-terrorist operation in Dagestan from 0515 GMT," the National Antiterrorism Committee said, according to Russian news agencies.

Authorities said 15 police officers and several civilians were killed by armed militants in attacks at two orthodox churches, a synagogue and a traffic police post in the cities of Derbent and Makhachkala on Sunday.

Six gunmen were later killed in a counterterrorist operation.

(With input from agencies)