The commander of Ukrainian forces trapped by Russian troops under a steel plant in Mariupol issued what he said could be the “last appeal” of his life on Tuesday, begging world leaders, including President Joe Biden, for help negotiating safe passage out of the besieged city in eastern Ukraine.

Maj. Serhiy Volyna of Ukraine’s 36th Separate Marine Brigade posted a video on Facebook saying his men and “hundreds of civilians” are facing their last hours alive underneath the Azovstal steel plant in Mariupol. Volyna said Russian troops outnumber his brigade “10 to 1” and that 500 are injured inside the shelter. Volyna implored Biden and other world leaders for help with “extraction” to a third country.