Authorities in Mariupol say people are coming out alive after successfully hiding in a bomb shelter at the theatre where hundreds of people, including children, were sheltering, prompting hopes of a miracle in the besieged Ukrainian city.

Sergiy Taruta, the local MP, announced the news on Facebook, which was translated by an official adviser to the Ukrainian government on Telegram.

“After a terrible and scary night of uncertainty on the morning of the 22nd day of the war, finally good news from Mariupol!” Taruta wrote.

“The bomb shelter withstood! The blockages began to be dismantled and people are coming out alive!”

The number of casualties and survivors is still unknown as the amount of rubble and debris created by the attack had made any recovery impossible. A search effort is now under way.

Private satellite firm Maxar released an image showing the word “children” written in Russian outside the theatre which was the target of a Russian attack on Wednesday.

Ukraine has said the bombing of the civilian target is yet another war crime committed by the Russians.

On Thursday, US President Joe Biden for the first time said Russia’s Vladimir Putin was a “war criminal.”