Ukraine's President Volodymyr Zelensky has told all civilians still living in parts of the eastern Donetsk region under Ukrainian control to evacuate.
Speaking during a late-night address from Kyiv, Mr. Zelensky said fighting in the region was intense.
"The more people leave Donetsk region now, the fewer people the Russian army will have time to kill," he said.
The region has seen heavy clashes amid a slow advance by Russian forces, who already control large parts of it.
"We will use all available opportunities to save as many lives as possible and to limit Russian terror as much as possible," the president added.
It is not the first time the Ukrainian authorities have told people to leave the area. Between 200,000 and 220,000 civilians still live in the unoccupied area of Donetsk, according to Ukrainian estimates.
An evacuation notice from the government warned the coming winter would make thing worse, especially for children.
"They need to be evacuated, you cannot put them in mortal danger in the winter without heating, light, without the ability to keep them warm," Kyiv's Ministry of Reintegration of Temporarily Occupied Territories said.
"Many refuse to leave, but it still needs to be done," Zelensky said.
Further, 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."