KHARKIV, Ukraine - A Russian drone attack struck residential buildings in the Ukrainian city of Kharkiv and an energy facility in the surrounding region on Thursday, killing four people and severing power for 350,000 residents, officials said.

Ukraine's second-largest city, which lies some 30 km (20 miles) from the Russian border, has been pounded by strikes during the 25-month war and been one of the worst afflicted as Russia has renewed its missile and drone attacks on the energy system.

Governor Oleh Synehubov said three rescue workers had been killed in a repeat strike after they reached a residential block hit in one attack. Writing on the Telegram messaging app, he said 12 people were injured, with three in serious condition.

Under floodlights in the night, emergency services raced to rescue a resident trapped under rubble and ladders reached up from fire trucks to shattered apartments at the top of high-rise blocks.

"Windows, all of the glass, everything was knocked out. There's nothing left," Zhanetta Kravchenko, a 77-year-old resident, told Reuters. "We are alive, at least, and I'm grateful for that."

Ukrainian broadcaster Suspilne reported that one of the strikes caused serious damage to apartments on three floors of a 14-storey building. It said emergency crews had been unable to work for at least an hour for fear of further strikes.

Residential buildings, stores, a medical facility and cars were damaged in the attack, the Kharkiv prosecutor's office said on Telegram.

Russia used at least 15 drones in the Kharkiv attacks, Synehubov said.

Ukraine's military shot down 11 Shahed drones out of 20 launched at the country overnight, the General Staff said.

Drones also hit the Zmiivska thermal power plant in the region, Synehubov said, keeping up pressure on an energy system that has come under repeated attack from air strikes in recent weeks.

"In Kharkiv and areas of the region, around 350,000 consumers have been disconnected," the Ukrenergo grid operator said in a statement.

Russian forces also hit a solar power plant in Dnipropetrovsk region, causing a fire which has since been put out, the Energy Ministry said. Some limits on energy consumption were also put in place in Dnipropetrovsk region on Thursday morning, the officials said.

Reuters was unable to independently verify the accounts. Russia denies deliberately targeting civilians in the war in which it is focusing on capturing eastern and southern parts of Ukraine.

An education facility, cultural centre and private residence in the Dnipropetrovsk region were also hit in the overnight attacks, the region's governor said, adding that no casualties were reported.

Kharkiv has been a frequent target of Russian drone and missile attacks.

Russian forces last week used an aerial bomb on the city, killing one person after a missile attack on an industrial area last month killed five people. REUTERS