At least four residents of the Russian-occupied Donetsk region in eastern Ukraine were killed in Ukrainian shelling on Monday, Kremlin-backed officialssaid.Three people were killed in the city of Donetsk and one in Horlivka to the north, according to the regions information center on Ukrainian attacks.Ten others were injured in attacks that damaged apartment buildings and passenger buses, the information center said.Footage published by the Kremlin-backed mayor of Donetsk showed the extent of the damage, including burnt homes, cars and buses.The Donetsk region's Russian-installed Governor Denis Pushilinconfirmed two fatalities and six injuries.Pushilin said the Ukrainian shelling destroyed a passenger bus without specifying whether there were people inside at the time.He added that a Ukrainian drone strike damaged water infrastructure in the city of Yasynuvata north of Donetsk.Ukrainian officials have not claimed responsibility for the reported strikes and it was not immediately possible to verify the Russian-installed authorities claims.Pro-Russian separatists in the Donetsk region and the neighboring Luhansk region had been locked in a simmering conflict with Kyiv's forces between 2014 and the start of Russia's full-scale invasion of Ukraine this year.Russia claims to have annexed the two regions after staging referendums this fall which were widely dismissed as a sham by outside observers.