The City council in Mariupol, which has been one of the hardest-hit areas since Russia invaded Ukraine at the end of February, claimed that Russian troops have been utilizing mobile crematoriums to hide civilian casualties. "Killers cover their tracks. Russian mobile crematoriums have started operating in Mariupol," Mariupol city council reported on Wednesday via Telegram. "They collect and burn the bodies of Mariupol residents murdered and killed as a result of the Russian invasion," they added, warning that last week's estimate of 5,000 deaths could balloon up to "tens of thousands." Mariupol, Ukraine's southern port city, has seen Russian occupation for weeks. By taking Mariupol, Russia would be able to gain a land bridge between Ukraine and Crimea, which was annexed by Russia in 2014. Russian forces in the north and east would also meet if Mariupol were to fall. Civilians have been unable to escape the city and have been trapped and cut off from electricity, gas and running water. Russian forces have hit multiple civilian buildings in the city including a children's hospital, art school and theater which were providing shelter to refugees. "The world has not seen the scale of the tragedy in Mariupol since the Nazi concentration camps. The Russian fascists turned our whole city into a death camp," Mariupol's Mayor Vadym Boichenko said in the Telegram post. "Unfortunately, the eerie analogy is gaining more and more confirmation. This is no longer Chechnya or Aleppo. This is the new Auschwitz and Majdanek. The world should help punish Putin's villains."