Russia bombarded Ukraine’s second-largest city with massive strikes in the early hours of Saturday, its mayor said, one night after Moscow carried out one of the war’s largest aerial assaults on Ukraine.

Russia attacked the eastern Ukrainian city of Kharkiv at night and in the evening with drones, missiles and guided bombs, killing at least four people and injuring more than 60, including a baby, local officials said on Saturday.

Russia claims Ukraine indefinitely postponed the release while Kyiv maintains it has been delayed until next week.