Russia carried out a strike on the city centre of Kramatorsk in Donetsk Region, taking people's lives, mayor Oleksandr Honcharenko said on Facebook.
Rescue services are working on the scene.
Donetsk governor Pavlo Kyrylenko quoted tentative reports as saying that russia used aviation rockets on the city.
"At least one civilian is known to have been killed. Residential high-rises in the centre of the strike are on fire. Emergency services are extinguishing the fire and helping people," he said.
Russia also targeted the city's plants.
Kramatorsk is bombarded by rockets and artillery daily. On 14 July, the enemy carried out an air strike on the city, damaging the Red Cross Ukraine office among others.