At least five people were killed in an upsurge in Ukrainian shelling in the Russian-backed rebel Ukrainian region of Donetsk on Monday, according to separatist officials.

Separatist leaders and Russian news outlets reported artillery strikes in Ukraine, including one on a market. Later, Russian news sources reported that a shell had landed on a maternity hospital in Donetsk, causing a fire and forcing personnel to evacuate patients to the basement.

There was no independent confirmation of any of the attacks and Reuters could not ascertain whether they had taken place. There has been no immediate reaction from Kyiv to the reports.

Russia’s state TASS news agency said separatist officials had reported five dead. Donetsk’s separatist leader Denis Pushilin pledged to mobilise more Russian forces to counter Ukraine.

Russian agencies reported that a child was among those killed and that at least 22 people were injured. On Monday evening, citing a Russian correspondent, they reported the shelling of the maternity hospital.

“Thanks to the quick action of staff, there were no injuries,” RIA news agency said.

U.N. spokesman Stephane Dujarric said officials had seen reports of the hospital attack.

“This is extremely troubling,” Dujarric said. “Any attack on civilian infrastructure, especially health facilities, is a clear violation of international law.”

The Donetsk News Agency earlier showed pictures of burning stalls at the Maisky market and several bodies on the ground.

“We had a hit to the market – there were many people here,” Yan Gagin, an adviser to the separatists’ self-styled government, told RIA news agency from the market.

Kremlin leader Vladimir Putin has repeatedly said that the main immediate reason for what he casts as a “special military operation” in Ukraine is to protect the Russian-speakers of the two regions in Donbas from persecution and attack by Ukraine.

Ukraine routinely denies carrying out any attacks on the two regions, the Donetsk and Luhansk People’s Republics, where separatists seized large swathes of land in 2014.

Ukraine and its Western backers say Russia is waging an unprovoked war against a sovereign state.

Russia denies targeting civilian sites in its military action, though the incursion has caused thousands of casualties and destroyed entire Ukrainian towns.