Russian forces are stepping up their strikes in Donetsk, worsening the already tough conditions for residents following Moscow's illegal annexation and declaration of martial law in the eastern province, Ukrainian authorities said.
The attacks have almost completely destroyed the power plants that serve the city of Bakhmut and the nearby town of Soledar, the region's Ukrainian governor Pavlo Kyrylenko said.
The shelling killed one civilian and wounded three, he reported late Saturday.
"The destruction is daily, if not hourly," Kyrylenko said in a state television interview.
In Bakhmut, some 15,000 remaining residents have been living under daily shelling and without water or power, according to local media.
The city had been under attack for months, but the bombardment picked up after Russian forces experienced setbacks during Ukrainian counteroffensives in the Kharkiv and Kherson regions.
Moscow-backed separatists controlled part of Donetsk for nearly eight years before Russia's full-scale invasion of Ukraine in late February.
Protecting the separatists' self-proclaimed republic was one of Russian President Vladimir Putin's justifications for the invasion, and his troops have spent months trying to capture the entire province.
While Russia's "greatest brutality" was focused in the Donetsk region, "constant fighting" continued elsewhere along the front line that stretches more than 1,000 kilometres, Ukrainian President Volodymyr Zelenskyy said in his nightly video address.
Between Saturday and Sunday, Russia's launched four missiles and 19 airstrikes, impacting more than 35 villages in seven regions -- from Chernihiv and Kharkiv in the northeast to Kherson and Mykolaiv in the south -- according to the president's office.
Russia has focused on striking energy infrastructure over the last month, causing power shortages and rolling outages across the country.
The capital, Kyiv, was scheduled to have hourly blackouts rotating Sunday in various parts of the city of some 3 million and the surrounding region.
Rolling blackouts also were planned in the Chernihiv, Cherkasy, Zhytomyr, Sumy, Kharkiv and Poltava regions, Ukraine's state-owned energy operator Ukrenergo said in a Telegram post.
Meanwhile, the Zaporizhzhia Nuclear Power Plant has been reconnected to Ukraine's power grid, local media reported Sunday.
Europe's largest nuclear plant needs electricity to maintain its vital cooling system, but it had been running on emergency diesel generators since Russian shelling severed its outside connections.