At least two people were killed in a Ukrainian rocket attack on the southwestern Belgorod region on Monday afternoon after thousands of residents were left without power due to an earlier drone barrage.

Belgorod region Governor Vyacheslav Gladkov said one of the people killed was a worker who was helping to restore power to homes in the region. He did not say where and when the attack happened, though unconfirmed reports from Telegram news channels suggested an electric station in the city of Belgorod was targeted in the rocket attack.

Gladkov said the second person, a man, died at the hospital as a result of injuries sustained in the strike.

Earlier, the governor said that around 40,000 residents in the Belgorod region were initially left without power following Ukrainian drone attacks on local energy infrastructure. As of Monday morning, at least 5,400 residents were still without power.

Russia’s Defense Ministry said on Monday that its air defense systems destroyed 251 Ukrainian drones overnight, marking one of Ukraine’s largest retaliatory attacks on Russia this year.

In the western Bryansk region, where its governor had warned residents twice about incoming drone strikes, emergency authorities told local media that energy infrastructure was damaged due to three “man-made fires.”

The Telegram news channel Astra said it identified one of the locations of a Ukrainian drone strike in the Bryansk region as the Klintsy power station. Bryansk region Governor Alexander Bogomaz said eight Ukrainian drones had been intercepted overnight, causing no injuries but triggering responses from emergency crews.