Ukrainian President Volodymyr Zelenskyy announced Saturday a mandatory evacuation for residents of the country's eastern Donetsk region amid intense fighting in the ongoing war with Russia.

The president said, "The more people leave [the] Donetsk region now, the fewer people the Russian army will have time to kill." He noted that those who do leave would be compensated.

Zelenskyy also said in his address that the hundreds of thousands of people still occupying combat zones in the larger Donbas region should leave as well. Donbas includes the Donetsk and Luhansk regions.

"Many refuse to leave, but it still needs to be done," he said. "If you have the opportunity, please talk to those who still remain in the combat zones in Donbas. Please convince them that it is necessary to leave."

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Ukraine president Zelenskyy

Ukrainian President Volodymyr Zelenskyy announced Saturday a mandatory evacuation for the eastern Donetsk region. (Ukrainian Presidential Press Office via AP)

According to Ukrainian media, Deputy Prime Minister Iryna Vereshchuk said the evacuation had to take place prior to the start of winter because the region's natural gas supplies had been destroyed.

But former U.S. ambassador to Ukraine John Herbst said the evacuation may have more to do with the anticipation of more fierce fighting instead of fuel shortages.

"I don’t know why Zelenskyy issued the call," he said. "What I do know is that there has been fierce fighting in Donetsk. The Russians took [neighboring] Luhansk [oblast] several weeks ago. I expect further fierce fighting in Donetsk."

The Ukrainian military claimed earlier on Saturday that more than 100 Russian soldiers were killed, and seven tanks were destroyed during fighting Friday in the Kherson region. The Kherson region is the center of Kyiv's counter-offensive in the south and a crucial part of Moscow's supply lines.

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Russian military truck

The Ukrainian military claimed earlier on Saturday that more than 100 Russian soldiers were killed, and seven tanks were destroyed during fighting Friday in the Kherson region.

Ukraine's southern command said rail traffic to Kherson over the Dnipro River had been cut, which could further isolate the Russian military west of the river from reaching supplies in Crimea and the east.

Long-range missile systems supplied by the West have been used by Ukraine to impose damage on three bridges across the Dnipro River in recent weeks, cutting off the Kherson region.

"As a result of fire establishing control over the main transport links in occupied territory, it has been established that traffic over the rail bridge crossing the Dnipro is not possible," Ukraine's southern command said in a statement.

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Russia-Ukraine conflict by the Dnipro River

Smoke rises behind vessels on the Dnipro River during Ukraine-Russia conflict in the Russia-controlled city of Kherson, Ukraine.

Kherson region Gov. Dmytro Butriy said the Berislav district, which is across the river northwest of the Kakhovka hydroelectric powerplant, was particularly damaged.

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"In some villages, not a single home has been left intact, all infrastructure has been destroyed, people are living in cellars," he wrote on Telegram.

Butriy said fighting was continuing in many parts of the Kherson region.

Reuters contributed to this report.