Mariupol Mayor Vadym Boichenko said more than 5,000 civilians — including at least 210 children — had been killed during weeks of Russian bombardment and street fighting in the southern Ukrainian city, which has been held under a devastating siege. He said Russian forces bombed hospitals, including one where 50 people burned to death.

Mariupol city officials said in a message posted to Telegram that mobile crematoria were being operated by Russian officials to burn the bodies of those that had been slaughtered, imagery that raised the specter of the 20th century’s greatest crime.

“The world has not seen the scale of the tragedy in Mariupol since the Nazi concentration camps,” Boichenko said in the statement. “The [Russians] have turned our whole city into a death camp.”

“This is no longer Chechnya or Aleppo. This is the new Auschwitz or Majdanek,” he said, imploring the international community to act.