Russian drones hit civilian targets and triggered a fire early on Friday in and near Kharkiv, Ukraine's second-largest city, officials said, but there was no immediate word on casualties.

Kharkiv regional governor Oleh Synehubov, writing on Telegram, said the attacks targeted civilian infrastructure after midnight in the city in Ukraine's northeast and also struck a locality in the region.

Kharkiv Mayor Ihor Terekhov said the fire was being brought under control, without elaborating.

The air raid alert in Kharkiv and other central regions was lifted 90 minutes after the initial reports, and there was no further word on the situation on the ground.

Alerts remained in effect in regions in the west, and the Ukrainian air force said Russian drones were in the air in three regions.

Maksym Kozytskyi, governor of Lviv region, on the Polish border, said anti-aircraft units had been active.