Air raid alerts sounded throughout Ukraine early on Friday, with some areas later reporting explosions and officials saying anti-aircraft units were in action in several regions.

The alerts extended to all regions of the country for about an hour from 2 a.m. (2300 GMT).

But there were no reports of strikes on infrastructure or civilian targets and no indications of casualties as the alerts were withdrawn in Kyiv and in central and southern regions.

Air raid alerts remained in force into the early morning throughout western Ukraine, but only in two regions in the east and Russian-annexed Crimea in the south.

The head of Kyiv’s military administration said Russian forces had sent successive waves of drones towards the capital, the 10th attack this month and the second in less than 24 hours.

“This Kremlin tactic is an attempt to overwhelm our anti-aircraft forces and put psychological pressure on civilians. It won’t happen!” Serhiy Popko wrote on Telegram.

“All air targets sent toward Kyiv were destroyed by our anti-aircraft defences.”

Several regions reported anti-aircraft units in operation.

Explosions were reported in widely separated regions, including Kriviy Rih in central Ukraine and Rivne and Lutsk in the west.

Ukraine’s military had said on Telegram that Russian aircraft were in the air and there was a threat of strikes from hypersonic Kinzhal missiles. An earlier military statement said some airborne targets had been downed, but gave no details.

The military had warned that central regions and Kyiv were at risk from drones.

Russia’s Tass news agency, quoting Russian-installed officials in the Moscow-controlled area of Donetsk region, said Ukrainian forces had fired eight grad missiles into the Russian-held city of Donetsk after midnight.

There were no details of damage or casualties.

Reuters was unable to verify details of any of the reported military activity.