Islamic State has claimed responsibility for an attack in Russia on Tuesday night.
Two vehicles were blown up by an explosive device in the Dagestan region. It is not yet clear how many are dead. Russian police said one officer was killed and two injured, whereas an ISIS-affiliated news channel said the death toll stood at 10.
"Two cars were blown up, the type of explosive device has not been established yet," Fatina Ubaidatova, a spokeswoman for the Dagestani police, told Reuters.
The Amaq news agency, which supports ISIS, posted a statement online saying its local affiliate was behind the attack.
ISIS has in the past said it was behind violent attacks on security forces in the North Caucasus, the volatile mainly Muslim part of Russia where Dagestan is located. Critics of the Kremlin have said widespread poverty and corruption have fed religious extremism in the region. A number of militants in Dagestan have sworn allegiance to ISIS.
The region, which is next to Chechnya on the border with Georgia, saw similar attacks on police in February. In the 1990s Moscow led two wars against seperatists in Chechnya which may have fuelled resentment among locals.
Tuesday's attack comes after it emerged that since Putin's announcement of a partial withdrawal from the Syria conflict, Moscow has in fact shipped more equipment and supplies to Syria than it has brought back in the same period. The analysis by Reuters suggests Russia is working hard to maintain military infrastructure in Syria and keep Assad's army supplied.
Putin has been engaged in a campaign to shore-up Syrian President Assad's regime against rebel forces. The Kremlin said Russian air strikes would only target ISIS' territories but analysis has shown many of its bombings have hit Western-backed rebel forces.
Additional reporting from Reuters.