A large Russian drone and missile attack on Kyiv early on Monday killed at least six people and injured nearly 20, the local authorities said — the latest in a series of deadly and intensifying Russian strikes on Ukraine.

The six people killed appeared to have been in a residential building that was struck. Ukraine’s emergency services released photos showing part of the five-story structure collapsed into rubble. As crews worked to clear the debris, officials warned that more people were probably still trapped beneath the wreckage.

The Ukrainian Air Force said Russia had launched more than 350 drones and decoys during the attack, as well as firing 16 ballistic missiles. It said it had intercepted most of the drones and three-quarters of the missiles. The figures could not be independently verified.

It was the second lethal barrage on Kyiv in the past week. Last Tuesday, 28 people died in a Russian assault, most of them the victims of a strike on another apartment building. That was the deadliest attack on the Ukrainian capital in nearly a year.

The new salvo of strikes has reinforced many Ukrainians’ belief that Moscow is not interested in a cease-fire, especially as its military pushes ahead with a summer offensive in eastern Ukraine. A strike on Sunday in Kramatorsk, a city near the eastern frontline, killed four people.

“Russia is once again striking at human lives and destinies. This is not a trend, not an accident — it is a plan,” Tymur Tkachenko, the head of Kyiv’s military administration, said on Monday after the attack.