At least 17 people have been killed by Russian missile strikes on the south-eastern city of Zaporizhzhia, the Ukraine defence ministry has said.
Dozens more were wounded, and several residential buildings destroyed.
The city is under Ukrainian control, but it is part of a region that Russia claimed it annexed last month.
Zaporizhzhia has been hit repeatedly in recent weeks, as Russia hits back at urban areas after suffering defeats in the south and north-east of Ukraine.
Parts of the Zaporizhzhia region, including its nuclear power plant – which is around 30 miles (52km) from the city – have been under Russian control since early in the invasion.
The Ukrainian regional governor in Zaporizhzhia, Oleksandr Starukh, said 12 Russian missiles partially destroyed a nine-storey building, and levelled five other residential buildings.
“There may be more people under the rubble. A rescue operation is under way at the scene. Eight people have already been rescued,” he said on Telegram.
Ukrainian President Zelensky called the shelling “merciless strikes on peaceful people again”.
“Absolute meanness,” he said. “Absolute evil. Savages and terrorists. From the one who gave this order to everyone who fulfilled this order. They will bear responsibility. For sure. Before the law and before people.”
At the plant itself, the head of the International Atomic Energy Agency (IAEA), Rafael Grossi, said on Saturday the security situation had deteriorated further after overnight shelling the previous night cut all external power.
The plant now relies on diesel generators for the electricity it needs for reactor cooling and other essential nuclear safety, Mr Grossi said.
The IAEA is pushing for a protection zone to prevent further damage to the site. Russia and Ukraine have blamed each other for the shelling.
Meanwhile, Russian divers are beginning a fuller examination of the damage done by Saturday’s explosion on the road and rail bridge linking occupied Crimea with Russia.
Though limited traffic has resumed along one lane, a section of the bridge was brought down by the blast.
Security has been tightened and Russian President Vladimir Putin has ordered a full investigation.