A suicide grenade attack outside a Moscow supermarket killed only the perpetrator, according to Russian news agencies.
Witnesses said the man drove to the store in north-east Moscow, disembarked from his car, muttered something, then detonated the grenade.
No clear motive for the suicide bombing has been reported.
However, the Interfax news agency quoted police as saying that the bomber was a 41-year-old who had told his son over the phone that he would commit suicide due to some apparent family dispute.
He was identified as coming from the Siberian province of Irkutsk.
The grenade bombing follows a suicide attack last month in Moscow's Domodedovo airport which killed 37 people. Chechen warlord Doku Umarov took credit for that bombing, blaming it on Russian crimes in the Caucasus. In a video posted online, he warned of future attacks.