STORY: Boichenko also estimated as many as 1,000 civilians may be sheltering in the Azovstal steelworks, where the remainder of Ukrainian troops in Mariupol are holed up and resisting the Russian siege.
Ukrainian President Volodymyr Zelenskiy has said as many as 120,000 civilians are blocked from leaving.
Boichenko said a small convoy of buses had evacuated people from Mariupol on Wednesday (April 20) and was now headed for the city of Zaporhizhia which is under Ukrainian control.
Mariupol, once home to 400,000 people, has seen not only the most intense battle of the war but also its worst humanitarian catastrophe, with hundreds of thousands of civilians cut off for nearly two months under Russian siege and bombardment.
Russian President Vladimir Putin claimed victory in Mariupol on Thursday, declaring the port "liberated", despite leaving hundreds of defenders still holed up inside the giant Azovstal steelworks.