A 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 54, including five children, regional officials said on Wednesday.

The intense strikes with 17 drones sparked fires in 15 units of a five-storey apartment building and caused other damage in the city close to the Russian border, Kharkiv Mayor Ihor Terekhov said.

“There are direct hits on multi-storey buildings, private homes, playgrounds, enterprises and public transport,” Terekhov said on the Telegram messaging app.

“Apartments are burning, roofs are destroyed, cars are burnt, windows are broken.”

A Reuters witness saw emergency rescuers helping to carry people out of damaged buildings, administering care and firefighters battling blazes in the dark.

Nine of the injured, including a 2-year-old girl and a 15-year-old boy, have been hospitalised, Oleh Sinehubov, the governor of the broader Kharkiv region, said on Telegram.

He added that the strikes hit also a city trolley bus depot and several residential buildings.

There was no immediate comment from Russia. Kharkiv, in Ukraine’s northeast, withstood Russian full-scale advance in the early days of the war and has since been a frequent target of drone, missile, and guided aerial bomb assaults.

The attack followed Russia’s two biggest assaults of the war on Ukraine this week, a part of intensified bombardments that Moscow said were retaliatory measures for Kyiv’s recent attacks in Russia.

Both sides deny targeting civilians in the war that Russia launched on its smaller neighbour in February 2022. But thousands of civilians have died in the conflict, the vast majority of them Ukrainian.

“We are holding on. We are helping each other. And we will definitely survive,” Terekhov said. “Kharkiv is Ukraine. And it cannot be broken.”