Special operations against suspected Islamists are frequent in Russia's North Caucasus, but have been rare in Moscow and Saint Petersburg
Heavily-armed Russian special forces on Wednesday raided an apartment building in Saint Petersburg in an operation targeting North Caucasus militants, killing four suspects.
The FSB security service said in a statement quoted by Russian agencies that the raid was part of an operation to detain "wanted persons accused of participating in illegal armed groups in the North Caucasus". "Criminals were destroyed by return fire when they attempted to resist," the FSB said.
Russia's Investigative Committee added that four suspects, all of them in the same apartment, were killed in the raid and their bodies were now being identified. No ordinary civilians or law enforcement officials were injured, it said.
Three of the men killed were provisionally named by the National Anti-Terrorism Committee to Russian agencies as Zalim Shebzukhov, Astemir Sheriev, and Vyacheslav Nyrov. It said that these three were leaders of the "terrorist underground active in Kabardino-Balkharia" in the North Caucasus. It said that no ordinary civilians or law enforcement officials were injured.
TV footage showed heavily-armed men in balaclavas cordoning off the multistorey apartment block on the outskirts of the northwestern city famed for its tsarist-era palaces.
"I heard several explosions and then a series of what sounded like gunshots," a man who said he was a resident of a neighbouring apartment building told Rossiya 24 television.
Special operations against suspected Islamists are frequent in Russia's North Caucasus region but have been rare in Moscow and Saint Petersburg in recent years.
Russia has battled a simmering insurgency in the Caucasus ever since fighting two brutal separatist conflicts with Chechnya. Many Islamists have left for Syria and there has been little violence linked to the North Caucasus spilling out of the region in recent years, with the last such attacks in the southern city of Volgograd in 2013.