The mayor of Mariupol, Ukraine, told The Associated Press on Monday that more than 10,000 civilians have been killed since Russian troops surrounded the port city, and he fears the death toll could soon reach 20,000.

Vadym Boychenko spoke to AP by phone on Monday, painting a grim picture of life inside the city under siege. He said the bodies of civilians are “carpeted through the streets,” and accused Russian forces of purposely blocking humanitarian convoys from bringing much-needed food, medicine, and other supplies to the city.

The city has been bombarded by shelling, and Boychenko accused Russian troops of bringing the bodies of dead civilians to a shopping center with storage facilities and refrigerators and using trucks that have been turned into mobile crematoriums to dispose of them. The mayor is in Ukraine but not Mariupol, and told AP several people have been keeping him up to date on what Russian forces are doing with the corpses.

Boychenko estimates that 120,000 civilians in Mariupol are in immediate need of food, clean water, and electricity. Ukrainian officials have said Russian forces set up “filtration camps” for residents of the city, and after processing they are sent to Russia or areas of Ukraine held by Russian-backed separatists. Boychenko told AP at least 33,000 people have gone through the camps, and those who do not pass the “filtering” are moved to improvised prisons. Read more at The Associated Press.