The U.S. Coast Guard is investigating what seems to be an oil spill just 20 miles north of the Deepwater Horizon oil rig, which is where the BP spill occurred. The leaky rig may be the Matterhorn SeaStar, owned by W&T Offshore, Inc. The slick is said to be 30 miles off the coast of Louisiana.

Not Again: Another Oil Spill Reported Near BP Explosion Site in Gulf

According to reports, two callers contacted the National Response Center on Friday, reporting that they had seen an oil slick in the water:

A helicopter crew and pollution investigators have been dispatched to Main Pass Block 41 in response to two calls to the National Response Center, the federal point of contact for reporting oil and chemical spills, said Paul Barnard, an operations controller for Coast Guard Sector New Orleans.

The first caller, around 11 a.m., described a sheen of about a half-mile long and a half-mile wide, he said.

About two hours later, another caller reported a much larger sheen — about 100 miles long — originating in the same area and spreading west to Cocodrie on Terrebonne Bay, Barnard said.

“We haven’t been able to verify that, and it would be very unlikely for an individual to be able to observe a 100-mile long sheen,” he said, adding inspection teams were en route around 3 p.m. to the site.

The Huffington Post is reporting that “the slick was sighted by a helicopter pilot on Friday and is about 100 miles long. A fishing boat captain said he went through the slick yesterday and it was strong enough to make his eyes burn.”

The AP is reporting today that the Coast Guard is investigating whether the material seen in the water is actually oil: “officials are collecting samples to determine what it is.”