KYIV, Ukraine — Russia attacked Kyiv with an hourslong barrage of missiles and drones, killing at least nine people and injuring more than 70 in its deadliest assault on the Ukrainian capital since last July and just as peace efforts are coming to a head.

A Russian drone hit a bus carrying workers in the Ukrainian city of Marhanets on Wednesday, killing nine people and injuring close to 50, Kyiv officials said, in an attack President Volodymyr Zelenskiy said was a "deliberate war crime".