Ukraine launched a massive drone attack on the Russian capital on Sunday, with two people killed in the surrounding Moscow region.

Axar.az reports, citing Reuters, that Moscow Mayor Sergei Sobyanin said more than 1,600 drones had been shot down across Russia since the previous day, including 450 that were approaching Moscow.

A drone also struck a residential building in the Moscow region, although no deaths were reported there. Sobyanin said the attack was intended to disrupt Russia’s parliamentary election but failed to do so.

The Moscow oil refinery was also hit in the attack. Reuters witnesses reported hearing explosions in the capital and seeing smoke rising from the refinery site, although the extent of the damage was not immediately clear.

Airports in Moscow imposed restrictions on arrivals and departures, leading to flight cancellations and delays. Russian authorities also reported casualties in the wider Moscow region.