A gunman opened fire on Sunday in a Russian Orthodox cathedral on the island of Sakhalin, off Russia's eastern coast, killing a nun and a churchgoer and wounding six other people, officials said.
The shooting happened as Russian security forces are on high alert due to concerns about possible attacks on the Winter Olympics in Sochi, thousands of kilometres (miles) to the west. There was no apparent link to the Games.
The gunman was detained at the scene after the shooting at the main cathedral in the city of Yuzhno-Sakhalinsk, on the island in the Sea of Okhotsk, north of Japan, the federal Investigative Committee said.
It added that the suspect had worked as a security guard in Yuzhno-Sakhalinsk, some 6,650 km (4,130 miles) from Moscow.
There have been a handful of shooting sprees in offices and public places in Russia in recent years, but they are relatively rare and state-run media tend to treat such attacks as a largely American phenomenon.
The Feb. 3 shooting at a Moscow school, in which a student used his father's rifles, has led to calls for stiffer punishment for gun owners whose weapons are used in attacks.