KYIV (Reuters) - A series of explosions resounded throughout the Ukrainian capital early on Saturday as air defence units engaged Russian drones, Reuters witnesses said.
Explosions were reported on both banks of the Dnipro River that runs through the city.
There were no immediate reports of casualties or serious damage.
Mayor Vitali Klitschko said anti-aircraft units went into action as groups of drones flew near the city. He said Russian forces were targeting areas near the city centre.
Anti-aircraft activity was heavy, he said, in Darnytskyi district on the east bank of the Dnipro and explosions also struck historic Podil on the opposite bank.
The Reuters witnesses reported loud blasts just after midnight. A new series of explosions over the next 45 minutes hit areas near Kyiv's central districts.
The witnesses said air raid sirens went off on the eastern bank of the Dnipro River, but on the western bank police warned residents of the air raid through loudspeakers.
Authorities warned of possible missile attacks in areas of Kyiv region surrounding the capital, where explosions were also reported.
Air raid alerts remained in effect in a swathe of territory stretching through the country's central regions.