Two people were killed in a Ukrainian drone attack on the Moscow region, local authorities said Sunday. An oil refinery was among the sites hit, while another drone struck an apartment, according to Moscow Mayor Sergey Sobyanin.

Sobyanin said more than 1,600 drones had been intercepted across Russia since Saturday, including 450 directed at Moscow. He described the assault as one of the largest Ukrainian drone attacks on the capital since Russia launched its full-scale invasion in 2022. The extent of the damage to the refinery was not confirmed.

Russia was holding the final day of a three-day parliamentary election when the strikes occurred. Sobyanin called the attack “unprecedented” and said it had been planned to disrupt the vote. The source did not provide independent confirmation of that claim.

Ukrainian President Volodymyr Zelenskyy said the refinery strike had a “very significant impact.” He said oil from the facility helped fund Russia’s war effort and called on Moscow to end the war. The source said energy infrastructure has repeatedly been targeted by both sides, despite US President Donald Trump saying they had agreed to stop such attacks.

In Ukraine, four people were killed in a Russian drone attack in the Kyiv region, local authorities said. The casualties included a mother and her two 3-year-old children; a girl injured in the attack later died in hospital. Homes and industrial buildings were damaged in the southwestern Fastiv district.

Separately, Russia’s state news agency RIA reported that a drone attack on a bus in the Russian-occupied part of Ukraine’s Kherson region killed two people, including an election official. The reported attacks came amid continued strikes on civilian areas and energy-related facilities on both sides.