At least one person has been killed and one injured in a shooting at the headquarters of Russia's Federal Security Service (FSB), reports said.
A gunman, who opened fire with an automatic weapon in the lobby of the building at Lubyanka Square in central Moscow, was killed by armed police, the BBC reported, citing Russian media.
There were reports also that three FSB officers were killed in the attack by three gunmen, but these were not confirmed by officials.