A Ukrainian official on Tuesday said that Russia is using mobile crematoriums to dispose of bodies in Mariupol in an attempt to cover up evidence of war crimes and hide the number of people that have died.

In an interview with CNN, Donestk region military governor Pavlo Kyrylenko said that Russian troops were taking the bodies in order to destroy them in “territory not controlled by Ukraine” in an attempt to hide “evidence of genocide.”

“They are using mobile crematoriums and mobile cremation machines and, also, taking people out, taking bodies of the dead in the street and the dead from collapsing buildings,” Kyrylenko said.

“They’re hiding, since the emergence of the evidence of war crimes in Bucha and the evidence of genocide. They’re now hiding the evidence” with the mobile cremation chambers, he added.

Kyrylenko’s comments come as Mariupol’s mayor on Monday said that more than 10,000 civilians could be dead in the city. Kyrylenko upped that estimate, saying officials are now looking at between 20,000 and 22,000 dead. 

He said Russian troops were refusing to let citizens leave the area in their private cars. 

Kyrylenko also said that he has seen reports of Russian troops using chemical weapons in Mariupol.

He said three people were injured during an alleged chemical attack with all in the hospital and recovering.

“I cannot 100 percent confirm a comment on [the reports]. I can, personally, confirm that there was this fact that this has happened and that it is fortunate that the people that were around there, our defenders, did not receive life threatening injury.”

The Pentagon on Monday said they have heard of the reports of chemical weapons usage but can not immediately confirm them.

“These reports, if true, are deeply concerning and reflective of concerns that we have had about Russia’s potential to use a variety of riot control agents, including tear gas mixed with chemical agents, in Ukraine,” press secretary John Kirby said.

Ukrainian President Volodymyr Zelensky said Monday night that Ukraine would take the threat of chemical weapons “very seriously” and called on Western countries to implement an oil embargo against Russia.