Moscow-backed separatists pounded eastern Ukraine’s industrial Donbas region on Friday, claiming to capture a railway hub as concerns grew that besieged cities in the region would undergo the same horrors experienced by the people of the port city Mariupol in the weeks before it fell.

Ukrainian officials warned that their forces wouldn’t be able to stop the Russian offensive without more sophisticated Western-supplied weaponry.

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The fighting on Friday focused on two key cities: Sievierodonetsk and nearby Lysychansk. They are the last areas under Ukrainian control in Luhansk, one of two provinces that make up the Donbas and where Russia-backed separatists have already controlled some territory for eight years.

Authorities say 1,500 people in Sievierodonetsk have already died since the war’s start scarcely more than three months ago. Russia-backed rebels also said they’d taken the railway hub of Lyman.

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The governor of Luhansk warned that Ukrainian soldiers may have to retreat from Sievierodonetsk to avoid being surrounded. But he predicted an ultimate Ukrainian victory. “The Russians will not be able to capture the Luhansk region in the coming days, as analysts predict,” Serhiy Haidai wrote on Telegram on Friday. “We will have enough forces and means to defend ourselves.”

Ukrainian President Volodymyr Zelesnsky also struck a defiant tone. In his nightly video address Friday, he said: “If the occupiers think that Lyman or Sievierodonetsk will be theirs, they are wrong. Donbas will be Ukrainian.”

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For now, Sievierodonetsk Mayor Oleksandr Striuk told The Associated Press that “the city is being systematically destroyed — 90% of the buildings in the city are damaged.”

Striuk described conditions in Sievierodonetsk reminiscent of the battle for Mariupol, located in the Donbas’ other province, Donetsk. Now in ruins, the port city was constantly barraged by Russian forces in a nearly three-month siege that ended last week when Russia claimed its capture. More than 20,000 of its civilians are feared dead.

Before the war, Sievierodonetsk was home to around 100,000 people. About 12,000 to 13,000 remain in the city, Striuk said, huddled in shelters and largely cut off from the rest of Ukraine. At least 1,500 people have died there because of the war, now in its 93rd day. The figure includes people killed by shelling or in fires caused by Russian missile strikes, as well as those who died from shrapnel wounds, untreated diseases, a lack of medicine or being trapped under rubble, the mayor said.