The top Russian-installed official in Ukraine's occupied Donetsk region, Denis Pushilin, accused Ukraine in a social media post of killing seven people on Friday, including a child, with a rocket that set a minibus alight in the city of Donetsk.
A Russian Investigative Committee officer who declined to give his name said a residential area had been struck by multiple Grad rockets.
He said all the passengers "including children" died, and the only survivor was the driver.
Reuters was unable to independently verify the number of casualties or who was to blame. Ukrainian officials did not immediately respond to a request for comment.
The Russian-installed mayor of Donetsk, Alexei Kulemzin, said on Telegram that 19 people had been wounded by shelling on Friday in various parts of the city, in addition to the seven who had been killed.
Donetsk, capital of the Ukrainian province of the same name, has been controlled by Russian proxy forces since 2014, but remains close to the front line of Russia's war with Ukraine.
Early on Friday, Russia launched its first large-scale air strikes on Ukraine in nearly two months, killing at least 21 civilians including several children.
