Ukrainian officials say Russia has bombed a theatre that was sheltering more than 1000 people, including children, in the city of Mariupol.
Foreign Affairs Minister Dmytro Kuleba described the attack as a "horrendous war crime", sharing an unverified photo of rubble where the Mariupol Drama Theatre reportedly stood.
The foreign ministry says people are trapped inside the destroyed building, with the number of casualties not known at this stage due to ongoing shellings.
"Putin's regime has long crossed the limit of humanity," it said, calling on the West to help "stop the atrocities of the Russian army".
Moscow has denied the attack.
Satellite image shows Ukraine's warning of children
Maxar satellite imagery from Monday shows the word 'children' written in large Russian script painted outside the theatre as a warning to Russian aircrafts.
Maxar is seeking new satellite images to verify the reports of an attack.
CEO Dan Jablonsky said in a statement shared with Yahoo that the company was committed to "supporting global transparency and combatting the spread of disinformation" through the release of its satellite imagery.
Mariupol's local council said a plane had dropped a bomb on the theatre, "purposefully and cynically destroying" it.
The Kyiv Independent's defence reporter Illia Ponomarenko said Russian troops were "animals" for ignoring the warning of children inside the building.
The city’s deputy mayor, Serhiy Orlov, said up to 1200 people were inside.
Russia's defence ministry denied any involvement, instead pointing the finger at the a far-right Ukrainian militia Azov Battalion, RIA news agency said.
Mariupol has been under attack for more than 10 days, with roughly 500,000 people trapped due to constant bombardment. The city's death toll is feared to have spread into thousands.
Mariupol is a coastal city located in the Donetsk Oblast region, which borders Russia in Ukraine's southeast and the focus of a territorial dispute with Russia-backed separatists.
Russian President Vladimir Putin has insisted the invasion is "going to plan" and says he is ready to discuss neutral status for Ukraine amid ongoing peace talks.
Do you have a story tip? Email: email@example.com.