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

Kyiv, Ukraine — Russia bombarded six regions of Ukraine in one of its largest aerial attacks of the three-year war, Ukrainian officials said Friday. The nighttime assault lasted for hours and killed three emergency responders in the capital Kyiv, according to authorities.

Russia launched waves of drones and ballistic missiles at multiple targets across a broad swath of Ukraine early Friday, killing at least four people in the capital and wounding around 40 across the country.