A Russian oil refinery was hit in a major Ukrainian drone attack on the Moscow region on Sunday, as Russia entered the final day of its three-day parliamentary election. The attack came as Russian strikes on Ukraine's Kyiv region killed at least four people, according to local authorities.

Two people were killed in the Ukrainian drone attack on the Moscow region, Russian officials said. Moscow Mayor Sergey Sobyanin said Russian air defenses had intercepted more than 1,600 drones since Saturday, including about 450 targeting the capital.

Sobyanin said numerous drones reached an oil refinery in the region, while another drone struck an apartment building. The extent of the damage to the refinery has not yet been independently confirmed.

Ukrainian President Volodymyr Zelenskyy said the strike had a "very significant impact," arguing that oil revenues from the facility help finance Russia's war effort. He called on Moscow to end the war and pursue peace.

Ukraine has repeatedly targeted Russian oil refineries and other energy infrastructure during the war. Such attacks have contributed to disruptions in Russia's fuel supply and increases in fuel prices, according to reports.

The latest attacks came despite US President Donald Trump saying that Russia and Ukraine had agreed to halt attacks on energy infrastructure.

Sobyanin described the drone assault as an "unprecedented attack" and said it appeared to have been planned to disrupt Russia's parliamentary election. Russian authorities have not provided independent evidence supporting that claim.

Meanwhile, in Ukraine's Kyiv region, Russian drone strikes killed four people, including a mother and her two 3-year-old children, Ukrainian officials said. A girl who was injured in the attacks was taken to a hospital in another district but later died.

The southwestern Fastiv district was also damaged, with homes and industrial buildings affected by the strikes.

Russia's Defense Ministry said its forces struck a warehouse belonging to Fire Point, a Ukrainian drone and missile manufacturer, in the Kyiv region. It also reported strikes on a cargo vessel and a postal logistics center in the Odesa region, alleging that both were being used to transport military supplies.

In the Russian-occupied part of Ukraine's Kherson region, meanwhile, a drone attack on a bus killed two people, including an election official, Russia's state-run RIA news agency reported.

The latest exchange of strikes underscores the continued escalation of attacks on energy and military-related infrastructure as the war enters another phase, with both sides continuing to launch long-range drone attacks despite diplomatic efforts to curb strikes on energy facilities.