Russian forces fired missiles at the centre of the eastern Ukrainian city of Kramatorsk in an air strike on Thursday, causing casualties, the city's mayor said.
"Air strike with missiles on central parts of Kramatorsk, there are casualties," Mayor Oleksandr Goncharenko wrote on Facebook, without providing details of the casualties.
"Stay in shelters, the danger is not over," he wrote.
Ukraine has said it expects Kramatorsk, in the Donetsk region, to be among the main targets for Russian forces following their capture of the city of Lysychansk on Sunday in the neighbouring region of Luhansk.
Vadym Lyakh, the mayor of Sloviansk, said earlier on Thursday that his city near Kramatorsk had also come under fire. He said some residents had been wounded but gave no details of the casualties.
Russia, which invaded Ukraine on Feb. 24, did not immediately comment on the situation in Kramatorsk or Sloviansk. It has denied deliberately targeting civilians.
After effectively cementing its total control of the Luhansk region, Moscow has made clear it is planning to capture parts of the Donetsk region that its forces have not yet seized.