A suicide bomber has blown herself up in the capital of the troubled southern republic of Dagestan, Makhachkala, officials say.
Fifteen people including five policemen were wounded in the attack, close to an interior ministry building.
Some of the victims were seriously hurt and at least one of the police officers was in a critical condition.
In recent years, Russia has seen a number of attacks by women suicide bombers, known as black widows.
They are often related to Islamist militants killed during a separatist campaign against Russia, particularly in the North Caucasus.
The bomber in Saturday’s attack, aged 25, was also thought to have been previously married to at least one militant, Russian news agencies reported.
“She has already been identified as Madina Aliyeva, a widow. Her two previous husbands were also killed as members of militant groups,” Magomedbek Akhmedov, a spokesman for Dagestan’s president, told Russian TV.
Her first husband was killed in 2009 and her second husband in 2012, a source told Interfax news agency.
A picture said to be of Madina Aliyeva was broadcast on state TV, and Russia’s National Counter-terrorism Commitee (NAK) said she had previously travelled abroad to contact illegal groups.