Russian drones hit residences early on Thursday in Kharkiv, Ukraine's second largest city, killing five people, including rescue workers hit in a repeat strike at the site of one attack, officials said.
Kharkiv Mayor Ihor Terekhov, writing on the Telegram messaging app, said four people died at the scene of one attack, at least three of them rescue workers killed after they had arrived at the scene and a new strike occurred. Five people were injured.
One person was killed in a strike on private homes in another city district, Terekhov said.
Kharkiv Regional Governor Oleh Synehubov said at least four strikes had hit the city and the top floors of one apartment building had been damaged. Three people were in hospital, with one in serious condition, he said.
Terekhov said one strike had triggered a fire, and part of another building had collapsed.
Reuters was unable to independently verify the accounts.
Kharkiv has been a frequent target of Russian drone and missile attacks.
Last week, Russian forces used an aerial bomb on the city, killing one person. A missile attack on an industrial area earlier in the month killed five people.
Terekhov said some city districts could be hit by power cuts. Russia in recent weeks has intensified its attacks on electricity and other infrastructure.