KIEV - Ukraine's second-largest city Kharkiv came under the "most intense" Russian attack early Saturday since the start of the two countries' conflict, said Mayor Ihor Terekhov.

According to preliminary data, Russia launched 48 Shahed combat drones, two missiles and four guided bombs at the city, resulting in more than 40 explosions, Terekhov said in a post on Telegram.

At least three people were killed, with 21 others, including two children, injured, and 18 apartment buildings, 13 private houses, a civilian enterprise and an educational institution were destroyed, he said.

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Ukraine's Air Force said Russia fired a total of 215 projectiles at Ukraine overnight, including 206 combat drones, a cruise missile Iskander-K and two ballistic missiles Iskander-M/KN-23, 174 of which were intercepted.