At least 15 people were killed and two dozen more are feared trapped after Russian Uragan rockets hit a five-storey apartment block in Ukraine’s Donetsk region, local officials said on Sunday as rescuers picked their way through rubble.

Ukraine also reported clashes with Russian troops on fronts in the east and south, while Moscow said its forces struck Ukrainian army hangars storing US-produced M777 howitzers, a type of artillery, near Kostyantynivka in Donetsk region.

Donetsk governor Pavlo Kyrylenko said the strike on the apartment building took place on Saturday evening in the town of Chasiv Yar. The regional emergency service gave the death toll at 15 on Sunday afternoon, adding that 24 more people could still be under the rubble.

“We ran to the basement, there were three hits, the first somewhere in the kitchen,” said a local resident who gave her name as Ludmila, speaking as rescuers removed a body in a white sheet and cleared rubble using a crane as well as their hands.

“The second, I do not even remember, there was lightning, we ran towards the second entrance and then straight into the basement. We sat there all night until this morning.”

Kyrylenko wrote on Telegram that rescuers in Chasiv Yar had cleared nearly 99 tonnes of rubble from the site of the collapsed apartment block, and that rescue operations were still going on as of 4 pm local time.

Andriy Yermak, chief of staff to President Volodymyr Zelensky, said in a Telegram post that the strike was “another terrorist attack”, and that Russia should be designated as a state sponsor of terrorism as a result.

Luhansk and Donetsk provinces comprise the Donbas, Ukraine’s eastern industrial region that has become Europe’s biggest battlefield for generations. Russia wants to wrest control of the Donbas on behalf of the separatists that it supports.

Russian forces attacked Ukrainian positions near the town of Sloviansk in Donetsk but were forced to withdraw, Ukraine’s military said, adding that Russian forces had launched a cruise missile attack on the northeastern city of Kharkiv from their side of the border. It gave no details of damage or casualties.

Luhansk region governor Serhiy Gaidai said Russian forces were gathering in

the area of the village of

Bilohorivka, about 50km east of Sloviansk.

“The enemy is... shelling the surrounding settlements, carrying out air strikes, but it is still unable to quickly occupy the entire Luhansk region,” he said on Telegram.

Russia claimed control over all of Luhansk province last weekend.

Russia’s defence ministry said its forces had destroyed two hangars near the Donetsk town of Kostyantynivka holding the US-made M777 howitzers, which it said had been used to shell residential areas of Donetsk.

Russian news agencies cited separatist officials as saying on Sunday that Ukraine’s military had been shelling Donetsk using Nato-standard 155mm artillery since the morning, wounding two residents.

Ukrainian military spokespersons were not immediately available for comment.

Ukrainian forces have mounted stiff resistance and the West has imposed sweeping sanctions on Russia in an effort to force it to withdraw.

In the south, Ukrainian forces fired missiles and artillery at Russian positions including ammunition depots in the Chornobaivka area, Ukraine’s military command said.

US secretary of state Antony Blinken, on a trip to Asia, urged the international community to join forces to condemn Russian aggression. He said he had raised concerns with his Chinese counterpart, Wang Yi, over Beijing’s alignment with Moscow.