The first heavy oil from the Gulf of Mexico spill has sloshed ashore in fragile Louisiana marshlands, and part of the mess has entered a powerful current that could carry it to Florida and beyond.
The new development underscores the gravity of the situation, the ABC reports, as BP strives to capture more crude gushing from a ruptured well 1.6 kilometres beneath the surface.
The spill is threatening an ecological and economic disaster along the US Gulf Coast and beyond.
"The day we have all been fearing is upon us today," Louisiana governor Bobby Jindal said after a boat tour to the southernmost point of the Mississippi River estuary.
"This wasn't tar balls. This wasn't sheen. This is heavy oil in our wetlands. It's already here but we know more is coming."
Leading producer of commercial seafood
Quoting Reuters reports, the ABC says officials had previously reported debris in the form of tar balls or light surface sheen coming ashore in outlying parts of Louisiana, Mississippi and Alabama.
The marshes are the nurseries for shrimp, oysters, crabs and fish that make Louisiana the leading producer of commercial seafood in the continental US and a popular destination for recreational anglers.
The US has already imposed a large no-fishing zone in Gulf waters affected by the spill.
Some has entered the Loop Current
The federal government's top weather forecaster says a small portion of light sheen from the slick has entered the Loop Current, which could carry the oil down to the Florida Keys, Cuba and even up the US East Coast.
The State Department says it has been holding talks with Cuban officials about the spill.
BP says it is now siphoning about 3000 barrels of oil day out of what the company estimated was a 5000-barrels-a-day gusher, and it could begin injecting mud into the well as early as Sunday in a bid to permanently plug the leak