Watch: Huge blast as drone explodes in Moscow
Russia's defence ministry has said three Ukrainian drones were downed on Sunday, with two crashing into offices.
Footage of an explosion near a Moscow building on Sunday was captured by nearby witnesses, and on a car's dashcam.
One person has been injured, Russia's state news agency Tass reports.
Russia accused Ukraine of being behind the attack and says one drone was shot down over the Odintsovo district, west of the city centre, and two others were neutralised but crashed into offices.
Ukrainian officials have not acknowledged the incident.