A Ukrainian drone attack ignited a fire at northwestern Russia’s Baltic Sea port of Ust-Luga, a major hub for oil exports, local authorities said early Tuesday.

Leningrad region Governor Alexander Drozdenko said air defense units intercepted 52 drones during a four-hour assault over the region.

“Damage and fire were recorded in the Ust-Luga port area as a result of the drone attack,” he wrote on Telegram, adding later that there were no casualties.

By around 9:30 a.m. Moscow time, Drozdenko said the fire was extinguished.

Ust-Luga, Russia’s largest shipping terminal on the Baltic Sea and second-largest nationwide behind Novorossiysk, was previously attacked by Ukrainian drones and caught fire on Aug. 14.