(Reuters) -Russia launched several waves of drone attacks on Kyiv early on Sunday for the second night in row, stepping up its assaults on the Ukrainian capital after several weeks of pause, the city’s military administration said.

“The enemy’s UAVs (unmanned aerial vehicles) were launched in many groups and attacked Kyiv in waves, from different directions, at the same time constantly changing the vectors of movement along the route,” Serhiy Popko, head of the Kyiv’s military administration, said on the Telegram messaging app.

“That is why the air raid alerts were announced several times in the capital.”

Ukraine’s Air Force said its air defence systems destroyed 15 of 20 Russia-launched Shahed kamikaze drones over Kyiv, Poltava and Cherkasy regions.

There had been no initial reports of “critical damage” or casualties, Popko said earlier. He also said that close to 10 of the drones were downed over Kyiv and its outskirts.

Cherkasy Governor Ihor Taburets said on Telegram that debris “slightly damaged” five houses but no people were injured. Kyiv’s region Governor Ruslan Kravchenko said an infrastructure object was damaged in the region. There were no casualties.

Reuters could not independently verify the reports. There was no immediate comment from Russia.

Russia started carrying out strikes on Ukraine’s energy, military and transport infrastructure in October 2022, six months after Moscow’s troops failed to take over the capital and withdrew to Ukraine’s east and south.

Last winter Russia pounded Ukraine with hundreds of missiles and drones, leaving millions without electricity, heating and water during the coldest months of the year, before easing the assaults in the summer.

After a pause of 52 days, Moscow resumed air strikes on Kyiv this month. On Saturday, Ukrainian officials said all drones heading towards Kyiv were destroyed but some hit infrastructure facilities elsewhere in Ukraine.

President Volodymyr Zelenskiy and other officials have warned that Russia would resume its large-scale bombardments of Ukrainian civilian infrastructure during the winter months.