At least four militants were killed on Thursday during a special police operation in Russia’s troubled North Caucasus republic of Chechnya, Chechen leader Ramzan Kadyrov said.

“The operation has been conducted since early morning in the mountainous area of the Vedensky district [in southern Chechnya],” Kadyrov said. “It is targeting an armed militant group, led by Muslim Gakayev, whose members were planning a number of serious crimes.”

Unfortunately, two police officers were also killed in a skirmish with militants, the Chechen leader said.

“The search for remaining militants will resume in the morning,” he added.

Sporadic terrorist attacks and clashes between police and militants are common in Russia's volatile North Caucasus republics, where Russia has held two brutal wars against separatists in Chechnya, although the Kremlin has officially ended its military campaign against separatists and terrorists there.