Russia and Ukraine continued aerial attacks on each other, inflicting injuries and damages, officials said early on Sunday, as the fate of a proposed ceasefire to the three-year-old war remained uncertain.

Russian President Vladimir Putin said on Thursday he supported in principle Washington’s proposal for a 30-day ceasefire with Ukraine but that his forces would fight on until several crucial conditions were worked out.

Both sides have since traded heavy aerial strikes, and Russia moved closer on battlefield to ejecting Ukrainian forces from their months-old foothold in the western Russian region of Kursk.

Early on Sunday, three people were injured, including a 7-year-old, in a Ukrainian drone attack on the Russian border region of Belgorod, regional Governor Vyacheslav Gladkov said on the Telegram messaging app.

Two of them were injured after a drone hit their house, sparking a fire in the Gubkinsky district of the region, while the other person was injured in a drone attack on the village of Dolgoye, Gladkov said.

Alexander Gusev, governor of the southwestern Russia region of Voronezh, said on Telegram that air defence units had destroyed more than 15 Ukrainian drones over the region. There was no immediate reports of injuries or damage, Gusev said.

The acting governor of the southern Russian region of Rostov said defence units repelled an overnight drone attack on the region, with no injuries or damage reported.

In Ukraine, authorities reported several Russian drone strikes, including on the northern region of Chernihiv, where firefighters were battling a blaze at a high-rise building that was sparked by Russian drone attack, Ukraine’s state of emergency service said.

Ukrainian media reported a series of explosions in the region surrounding the capital Kyiv, after Ukraine’s air force issued warnings of a threat of drone attacks on the Kyiv and a number of other central Ukrainian regions.

By 0300 GMT on Sunday, there was no official information about potential damage in the Kyiv region.