Unusually high waves attributed to the eruption of an undersea volcano in Tonga caused an oil spill on the Peruvian coast, but authorities said Monday the spill was controlled within hours and there’s an ongoing process to clean the area.

The Peruvian Civil Defense Institute said in a press release that a ship was loading oil into La Pampilla refinery on the Pacific coast on Sunday when strong waves moved the boat and caused a spill.