The bomb, planted in a parked car by unknown perpetrators, was detonated by remote control as two other vehicles were passing, reported the Interfax news agency on Thursday.
The driver of one of the vehicles was killed in the blast along with a passenger, the news agency quoted police as saying.
Five other people were treated at a hospital for their injuries. One of the wounded, who suffered minor injuries, was later released.
The explosive-laden car belonged to a local unemployed man who had sold it to an identified buyer two months ago, said police who have opened an enquiry.