VENICE, La. (AP) — Federal authorities said Saturday that they’re investigating a leak from an underwater oil pipeline off the coast of Louisiana.

The National Transportation Safety Board said on X, formerly known as Twitter, that it had sent a four-person team to do a safety investigation and determine the cause of the leak about 19 miles (31 kilometers) offshore from Venice, Louisiana. The agency said the pipeline is operated by Third Coast Infrastructure LLC.

The National Oceanic and Atmospheric Administration, or NOAA, said oil sheen was seen on water at around 9 a.m. Thursday and Third Coast Midstream Pipeline reported the leak 10 minutes later. A flight over the area at around 2 p.m. that day reported a slick that was 3 to 4 miles wide (roughly 5.5 kilometers) “with dark oil scattered throughout,” the agency said on its website.