A Russian airstrike has devastated a children's hospital with a maternity ward in the besieged port city of Mariupol and wounded at least 17 people, Ukrainian officials said.
Russia, which denies targeting civilians, had said it would hold fire to let civilians flee Mariupol and other besieged cities on Wednesday. But the city council said the hospital had been hit more than once.
Ukraine blamed Russia for breaking a ceasefire at the southern port as civilians elsewhere fled the fighting through safe corridors.
Hundreds of thousands of people in Mariupol have been sheltering under bombardment without water or power for more than a week. Many tried to leave on Tuesday along a safe corridor but Ukraine said they came under Russian fire.
"Ceasefire violated! Russian forces are now shelling the humanitarian corridor from Zaporizhzhia to Mariupol," Ukraine's foreign ministry spokesperson Oleg Nikolenko wrote on Twitter.
"Today Russia committed a huge crime," said Volodymir Nikulin, a top regional police official, standing in the wreckage. "It is a war crime without any justification."
Ukrainian President Volodymyr Zelenskyy wrote on Twitter that there were "people, children under the wreckage" and called the strike an "atrocity". Video shared by Zelenskyy showed cheerfully painted hallways strewn with twisted metal.
"There are few things more depraved than targeting the vulnerable and defenceless," British Prime Minister Boris Johnson wrote on Twitter, adding that Russian President Vladimir Putin will be held "to account for his terrible crimes".
A Russian spokesman meanwhile blamed Ukraine for the failure of a planned evacuation from Mariupol.
Russian troops are pressing closer to Ukraine capital Kyiv and citizens fear that the city will be encircled. In the city's central square, an orchestra played Europe's anthem "Ode to joy" on Wednesday to boost morale.
Around 35,000 people were evacuated through humanitarian corridors from three cities on Wednesday, Ukrainian President Volodymyr Zelensky said. Local officials said civilians had left Sumy in the east and Enerhodar in the south.
Over 2 million people have fled Ukraine since the invasion began two weeks ago.