At least two people have been killed and six injured in a "massive" overnight Ukrainian drone attack on the Moscow region, Governor Andrei Vorobyev has said.
Moscow Mayor Sergei Sobyanin said 450 drones heading for the capital had been shot down in what he called an "unprecedented attack". The city's main oil refinery was damaged and several homes were set ablaze.
Ukraine's President Volodymyr Zelensky confirmed Kyiv had hit a "key" Russian oil facility and a logistics site in the region, representing "billions of dollars that sustain the war machine".
Ukrainian officials meanwhile said nine people, including three children, had been killed in Russian attacks in the Kyiv and Sumy regions on Saturday.
The overnight attack is thought to be among the largest drone attacks on the Moscow region since the war began.
Russia and Ukraine have recently intensified their strikes, targeting energy-generating and transport facilities, as well as major logistics hubs.
A 44-year-old woman was killed in Sofyino on Sunday after a drone hit a three-storey residential building, regional head Vorobyev said. Another five people - including two children - were injured.
An elderly man died after a private house was hit in the Orekhovo-Zuevo district, Vorobyev added.
Videos have emerged on social media appearing to show explosions in the night skies above Moscow, and a burning warehouse. The footage has not been verified by the BBC.
Mayor Sobyanin said a drone had struck a building near one of the capital's boulevards and the oil refinery - where Ukrainian military officials said three key units had been damaged.
The site supplies more than a third of the Moscow region's fuel, according to the defence ministry in Kyiv, and some of its petrol, diesel and aviation fuel go to Russia's military.
Ukraine's defence minister said attacking such facilities "directly undermines the enemy's ability to continue its war of aggression and supply its military formations".
Sobyanin said the major attack was "an attempt to disrupt" Russia's parliamentary election, which was in its third day on Sunday. The vote is tightly controlled by the Kremlin and has been dismissed by critics as neither free, fair nor transparent.
Russian state media reported that an election official was one of two people killed by a drone attack on a bus in a Moscow-controlled part of Kherson in Ukraine on Sunday, citing the head of Russia's election commission.