NORSI (Nizhny Novgorod Oil Refining Company), Russia’s fourth-largest oil refinery and the country’s second-largest gasoline producer, halted oil processing on Wednesday following a Ukrainian drone attack.

Three industry sources told Reuters, Ukrinform reports.

According to the sources, the drone attack damaged several processing units, inter-unit infrastructure and general plant facilities. They were unable to say how long it would take to repair the damage ⁠and resume processing operations at the refinery.

On August 26, a Ukrainian drone attack damaged an industrial facility in Russia’s Nizhny Novgorod region, regional Governor Gleb Nikitin said on Wednesday.

Lukoil, which owns the refinery, did not comment on the attack.