Several people were killed and many more injured in a series of what officials called terrorist attacks in the republic of Dagestan in Russia's North Caucasus region.
Unknown assailants opened fire on a synagogue and an Orthodox church in the southern Russian city of Derbent, state news agency TASS reported on Sunday.
A fire broke out in the synagogue following an exchange of fire. At the same time, a police station and another church were attacked in the regional capital of Makhachkala, more than 100 kilometres away.
"According to preliminary information, one Orthodox priest and several police officers were killed in the terrorist attacks," the Russian Investigative Committee said.
Interfax news agency quoted security officials as counting six dead and 23 injured police officers.
Two assailants are also said to have been killed in the exchange of fire, and a manhunt for further perpetrators is under way. Authorities say they have opened criminal proceedings.
The governor of Dagestan, Sergei Melikov, described the attack on Telegram as an attempt to destabilize the situation in the region. Dagestan, with a largely Muslim population, is one of the poorest regions in Russia.