Devastating pictures have shown the ruins of the Mariupol theatre after the building where civilians were sheltering was attacked by Russian forces.
The death toll from the attack is unknown but as many as 2,000 people were thought to have been in the building.
In an address to the nation, Ukrainian President Voldymyr Zelensky said: “Russian aircraft purposefully dropped a huge bomb on the drama theatre in the city centre.
"Hundreds of people were hiding from the shelling there. The building was destroyed. The death toll is still unknown.”
The word “children” was seen written in large letters outside the theatre in a sattelite image from before the attack.
Regional governor Pavlo Kirilenko said: “Russians purposely attacking civilians.
“These b******s are aiming to physically destroy Mariupol and Mariupol citizens, who have long become a symbol of our resistance.”
The city has been one of the worst hit in the country, with Ukrainian officials saying at least 2,400 people have been killed.
Thousands more are trapped in the city with officials warning a humanitarian crisis is taking place due to low food, water, and medicine supplies.
The deputy mayor said up to 1,500 cars managed to escape the city on Wednesday.
Kyrylo Tymoshenko, a senior aide to the Ukrainian President, said Russia had also blocked a humanitarian aid convoy trying to reach the city.
According to the UN’s latest update on March 16, 726 civilians people have been killed in Ukraine, although it is thought that number may be higher.