The mayor’s office in a key eastern Ukrainian city controlled by pro-Kremlin separatists was struck by rockets Sunday morning, Russian state agencies reported. There were no immediate reports of casualties.

According to RIA Novosti, the municipal building in Donetsk was seriously damaged by the attack, which local separatist authorities blamed on Ukraine.

Photos circulating on social media showed plumes of smoke swirling around the building, rows of blown-out windows and a partially collapsed ceiling. RIA Novosti and local media also reported that three cars parked nearby had burnt out as a result of the strike.

Kyiv didn’t immediately claim responsibility or comment on the attack.

Kremlin-backed separatist authorities have previously accused Ukraine of numerous strikes on infrastructure and residential targets in the occupied territories, often employing the U.S.-supplied long-range HIMARS rockets, without providing corroborating information.

The strikes came a day after two men from a former Soviet republic fired at volunteer soldiers during target practice at a Russian military firing range near Ukraine, killing 11 and wounding 15 before being slain themselves. The Russian Defense Ministry, which reported the killings, called the incident a terrorist attack.

The incidents come amid a hasty mobilization ordered by President Vladimir Putin to beef up Russian forces in Ukraine amid a series of battlefield setbacks following his February invasion. The callup triggered protests and caused hundreds of thousands to flee Russia.

Also Saturday, a Washington-based think tank late accused Moscow of conducting “massive, forced deportations of Ukrainians” which it said likely amount to ethnic cleansing.

In its regular online update, the Institute for the Study of War referenced statements made this week by Russian authorities, which claimed that “several thousand” children from a southern region occupied by Moscow had been placed in rest homes and children’s camps in Russia amid an ongoing Ukrainian counteroffensive. The original remarks by Russia’s deputy prime minister, Marat Khusnullin, were reported by the state RIA Novosti agency on Friday.

The Institute also said that Russian authorities “may additionally be engaged in a wider campaign of ethnic cleansing by depopulating Ukrainian territory through deportations and repopulating Ukrainian cities with imported Russian citizens,” in violation of international humanitarian law.

Russian authorities have previously openly admitted to placing children from Russian-held areas of Ukraine, who they said were orphans, for adoption with Russian families, in a potential breach of a key international treaty on genocide prevention.

The 1948 Genocide Convention, which was ratified by over 140 states including Ukraine and Russia, includes “forcibly transferring children of the (targeted) group to another group” in its definition of genocide.

Elsewhere, the Ukrainian military on Sunday morning accused pro-Kremlin fighters of evicting civilians in occupied territories in order to accommodate officers in their homes, an act it also described as a violation of international humanitarian law.

The General Staff of the Armed Forces of Ukraine said in its regular Facebook update that the evictions were happening in the Russian-held city of Rubizhne, in the eastern Luhansk region where Kyiv has been pressing a counteroffensive. It did not provide corroborating evidence for its claim.

AP