According to the rescue services, 24 people are still under the rubble, including a child, while five others have been rescued from under the rubble following the partial collapse of the building.

Pavlo Kyrylenko, the Donetsk region's governor, said the strike took place on Saturday evening in Chasiv Yar, a town of some 12,000 inhabitants.

It lies about 20 kilometers southeast of Kramatorsk — a city that is expected to be a major target of Russian forces as they advance slowly westwards.

The Ukrainian emergency services initially gave a death toll of six, but later said it had risen to 10 before the latest toll of 15.

AFP reporters who arrived at the scene after the overnight strike saw the building partially collapsed, with rescue workers and an excavator working to clear the area.

"I was in the bedroom, I came out and everything started shaking, collapsing. What saved me was the wave of the explosion that propelled me into the toilet, all bloody. I barely got out," said one resident, who did not want to give her name.

According to one of the heads of the rescue operation, Vyacheslav Boitso, the rescue team managed to establish contact with three people who were alive under the rubble.

"There is a chance of finding them," he told AFP. "They have enough air, they can breathe. They tell us they are waiting to be rescued."

The Donetsk region is one of two provinces along with Luhansk that make up the Donbas region, where separatist rebels have fought Ukrainian forces since 2014.

Last week, Russia captured the city of Lysychansk, the last major stronghold of Ukrainian resistance in Luhansk.

On Saturday, Luhansk governor Serhiy Haidai said Russian forces were managing to “raise true hell” in Ukraine’s eastern industrial heartland.

Serhiy Haidai said Russia launched over 20 artillery, mortar and rocket strikes in the province the previous night and its forces were pressing toward the border with the Donetsk region.

After the seizure of Lysychansk, some analysts predicted Moscow’s troops likely would take some time to rearm and regroup.

But Haidai said that so far there had been "no operational pause announced by the enemy", which was "still attacking and shelling our lands with the same intensity as before".

Later he added that the Russian bombardment of Luhansk was suspended because Ukrainian forces had destroyed ammunition depots and barracks used by the Russians.

Ukrainian authorities said the Russian army continued to bomb Ukraine's eastern Donetsk and northeastern Kharkiv regions on Saturday. According to officials, Moscow is preparing "new actions" after four and a half months of war.