Emergency services respond to the suicide attacks in Grozny
At least four police have been killed in a string of suspected suicide bombings in Chechnya's capital, Grozny, with fears the death toll will rise.
Several blasts hit different areas of the city at around lunchtime, local officials said.
Russian forces have fought two wars against separatists in the mainly Muslim republic of Chechnya since 1994. The fighting claimed 100,000 lives.
Islamist violence has recently increased in Russia's North Causasus.
On Monday, 25 people were killed in a suicide attack on a police station in Ingushetia, a Russian republic that borders Chechnya.
Friday's alleged suicide bombers in Grozny apparently followed the same routine, says the BBC's Artyom Liss in Moscow: they approached police checkpoints on bicycles before blowing themselves up.
Several more police were wounded in some five attacks, officials said.
After the two brutal wars in Chechnya, a period of quiet seemed to have settled in the southern Russian republic, our correspondent says.
But in the last few months, the insurgency there - and in the neighbouring parts of Russia - seems to have resumed, he adds.
Attacks on police officers and military personnel becoming almost a daily occurrence across the Caucasus.