Russian missiles have hit a reservoir dam near the southern Ukrainian city of Kryvyi Rih, officials say.
Residents in some areas were told to evacuate, city chief Oleksandr Vilkul said, but he added that the situation was under control.
Ukraine said the attack was retaliation by Russia for its latest counterattack.
President Volodymyr Zelensky – who was born in the city – described Russia as a “terrorist state” after the attack on the Karachunivske reservoir.
“You are weak for fighting civilians,” Zelensky said in his speech late Wednesday night.
“Scoundrels who, having escaped from the battlefield, are trying to do harm from somewhere far away.”
This was an apparent reference to Ukraine’s recent military successes in a swift counteroffensive in the country’s northeastern Kharkiv region.
The Ukrainian army has recaptured parts of the occupied territory, forcing Russian troops to withdraw.
In his speech, Zelensky said that the reservoir had “no military value at all”.
Vilkul said two explosions were carried out overnight to increase the flow of water from the dam to the Inhulets River.
The water supply was affected by the attack on the city, which had a pre-war population of more than 600,000 people.
Water broke through the dam and overflowed the banks of the river, flooding several homes, officials said.
On Thursday morning, Vilkul said water levels in the Inhulets River had now “dropped significantly”. He said there were no casualties.