A concentrated, nine-minute-long Russian drone attack on Ukraine's second largest city of Kharkiv in the middle of the night killed at least two people and injured 57, including seven children, regional officials said on Wednesday.

One of the hardest-hit areas was the city of Kharkiv in northeastern Ukraine, where 17 attack drones struck two residential districts, Mayor Ihor Terekhov said. Emergency crews, municipal workers and volunteers worked through the night to extinguish fires, rescue residents from burning homes, and restore gas, electricity and water services.

Massive Russian strikes on Ukraine’s second-largest city killed at least five people on Saturday, officials said, one night after Moscow carried out one of the war’s largest aerial assaults on Ukraine.