Ukraine has repeatedly stated that it will not give up Crimea, a southern peninsula illegally annexed by Russia in 2014.
Russian President Vladimir Putin launched a full-scale invasion of Ukraine in 2022, and Moscow currently control about 20% of Ukrainian territory.
Ukraine’s state emergencies ministry DSNS and the interior ministry said that nine people were killed in Kyiv in the overnight Russian attack.
In a post on social media, Mayor Klitschko wrote that six children and a pregnant woman were among those injured.
“Fires broke out in six locations,” he said, adding that there “people are under the rubble” of a destroyed residential building.
Interior Minister Ihor Klymenko said that “phone calls can be heard from the wreckage”.
He also said that two children were reported missing.
Rescuer teams with sniffer dogs were seen combing through the wreckage as they searched for survivors.
The worst-hit was the western Svyatoshynskyi district of the capital, Klitschko said.
Footage has emerged on social media purportedly showing missiles hitting Kyiv, triggering huge blazes.
In Kharkiv, about 40km (25 miles) from the Russian border, two people were injured, Mayor Ihor Terekhov said.
He said “private houses” were damaged in the overnight Russian missile and drone attack.
Ukraine’s air force warned that virtually all the country’s regions were under the threat of air strikes.
The Russian military has not commented on the reported attacks.
In a post on social media, the Russian defence ministry said that 87 Ukrainian drones had been either destroyed or intercepted overnight over several Russian regions.
