At least five Russian security officers have been killed and a dozen others wounded in an attack carried out by gunmen in the Chechen capital, Grozny.
Russian media say some 15 gunmen travelling in several cars attacked a checkpoint in Grozny in the early hours of Thursday.
The militants also stormed a major local publishing house in the center of the city and reportedly set it on fire.
At least six gunmen were killed in the ensuing gun battles, authorities said.
Local officials have heightened security in the center of the north Caucasus city.
A source close to Russian security services say the assailants had seized the cars from a nearby village on Wednesday night.
A video has been posted online by an individual claiming responsibility for the attacks. He claims to be operating under orders from the Chechen militant leader, Aslan Byutukayev.
In October, five soldiers were killed and 12 others injured in a bomb attack in Grozny.
Russia’s southern Republic of Chechnya, along with neighboring Dagestan and Ingushetia, has been facing unrest recently.
Violence erupted in the volatile Republic of Chechnya in the aftermath of the collapse of the Soviet Union in 1991. The republic has witnessed two brutal wars between Chechen separatists and the Russian army in the 1990s and early 2000s.