Two female suicide bombers have detonated explosives on two packed Moscow metro trains during morning rush hour, leaving 37 people dead.
Another 30 have been wounded.
Officials say the attack is the worst in the Russian capital for six years, with suspicion likely to fall on Chechen separatists in Russia's North Caucasus. Chechen separatists were blamed for a train bombing that killed at least 39 people in 2004.
The Russian authorities say the latest explosions are being investigated as acts of terrorism.
Both explosions took place in central Moscow, with the first at the Lubyanka station, next door to the headquarters of Russia's FSB security service.
Police say the dead include 14 people inside a train and 11 on the platform.
The second explosion occurred about 40 minutes later at the Park Kultury station, where 12 people died.
The BBC's Moscow correspondent says no-one has yet claimed responsibility, but the explosions do appear to have been co-ordinated.
