The attack on Friday, which killed at least four people in the capital, came two days after Russia vowed retaliation for an audacious drone assault on its strategic bomber bases.

Russia launched drones and ballistic missiles at multiple targets across Ukraine, Kyiv authorities said on Friday, in a deadly air assault that left at least four people dead and 20 wounded in the capital.

Officials say Ukraine was under an ongoing Russian ballistic missile and drone attack early Friday that wounded at least three people.