A suicide bomber has killed five police officers in Chechnya's capital, Grozny.
The Interior Ministry branch in Chechnya reported the bomber blew himself up on October 5 outside the venue where a concert marking Grozny's City Day was about to begin.
At least 12 people were injured in the attack.
Grozny's City Day celebrations coincided this year with the birthday of Chechnya's pro-Moscow president, Ramzan Kadyrov.
Russian news agencies reported that local police working a metal detector outside the concert venue became suspicious at the behavior of a young man in the crowd.
According to the Interior Ministry, when police approached the man he detonated the explosives he was carrying.
Local authorities said the bomber, who was also killed in the explosion, was tentatively identified as 19-year-old Opti Mudarov.
They said Mudarov was from the Staropromyslov district of Grozny, had left home two months ago, and had not been heard from since then.
Kadyrov offered a slightly different account of events outside the concert hall.
He said the bomber was armed with a pistol and was posing as a policeman and detonated his explosives when the real police officers said they wanted to search him.
Kadyrov credited the police for their professionalism and vigilance, which he said prevented what could have been a greater catastrophe.
Kadyrov said the "terrorists had attempted to turn a holiday into a national tragedy and spill the blood of dozens or hundreds of people."
Kadyrov's father, former President Akhmad Kadyrov, was killed in an explosion in Grozny in May 2004.
Russian Interior Minister Vladimir Kolokoltsev said the slain police officers would be given posthumous awards.
Kadyrov earlier in the day had been praising the changes in Grozny, saying the city was in ruins not so long ago but has been reborn.
He has recently said that Islamist extremists were no longer a threat in Chechnya.
Chechnya fought two separatist wars with Moscow in the 1990s that gradually turned into a fight for an Islamic state in the region led by a group calling itself the Caucasus Emirate.
The October 5 attack was the first major incident since the insurgents' longtime leader, Doku Umarov, was killed last year.
The last suicide bombings in Russia occurred late last year in Volgograd. The bombings of a train station and an electric trolleybus there killed 34 people.