They believe the blast was the result of a bomb in the stairwell, planted by common criminals settling scores among themselves. Because of petrol shortages, the pensioners had been storing gasoline in canisters outside their front door and they died in a fire after the initial explosion.
In Moscow yesterday, police found more stored explosives. Police say the terrorists brought the explosives, probably stolen from the army, into the capital in vans, whose innocent drivers thought they were carrying sacks of sugar.
An organisation calling itself the Dagestan Liberation Army has claimed responsibility for bringing the war in the Caucasus to Moscow. It says the bombings are in revenge for the deaths of Muslim women and children in Russian air raids.
Two Chechens were in custody in Moscow yesterday, accused of involvement in the terrorist attacks.