MOSCOW — A gunman killed a nun and a parishioner after spraying bullets into a church on Sakhalin Island off Russia’s Far East Coast, the state Investigative Committee said in a website statement.

Six other persons were wounded in the attack inside the Resurrection Cathedral on Yuzhno-Sakhalinsk, Sakhalin’s biggest city, according to the government. Police arrested the suspect, who worked as a security guard, at the scene, the government said.

The six wounded were shot in the legs and their lives aren’t in danger, RIA Novosti reported, citing Archbishop Tikhon, the regional prelate.

Russia’s security and police are on high alert because of concern about possible terrorist attacks in Sochi on Russia’s Black Sea coast where the Winter Olympics are being held. Special forces killed five suspected militants and took another into custody Saturday in the Russian republic of Dagestan, Rossiyskaya Gazeta reported, citing an unidentified law enforcement official.

Sochi lies west of the Caucasus mountains that stretch about 746 miles across Chechnya to Dagestan and the Caspian Sea in one of Russia’s most economically distressed regions. Russian forces have responded almost daily to attacks in the region by Muslim extremists after two separatist wars following the collapse of the Soviet Union.

President Vladimir Putin said on Jan. 17 that 40,000 police and special services officers were being deployed in Sochi to ensure security at the Olympics, which started yesterday.

Security has been stepped up across Russia since two suicide bombings killed more than 30 people on Dec. 29 and Dec. 30 in the southern city of Volgograd.