An oil spill that is threatening to eclipse the Exxon Valdez disaster spread out of control and started washing ashore along America's Gulf Coast early today.
The spill, thought to be roughly the size of Jamaica, was bigger than imagined - five times more than first estimated - and closer.
Fingers of oily sheen were reaching the Mississippi River delta, lapping the Louisiana shoreline in long, thin lines.
"It is of grave concern," David Kennedy of the National Oceanic and Atmospheric Administration, said.
"I am frightened. This is a very, very big thing. And the efforts that are going to be required to do anything about it, especially if it continues on, are just mind-boggling."
The oil slick from the BP-operated Deepwater Horizon rig which exploded and sank a week ago could become America's worst environmental disaster in decades, threatening hundreds of species of fish, birds and other wildlife along the Gulf Coast.
The area is one of the world's richest seafood grounds, teeming with shrimp, oysters and other marine life.
The oil was thickening in waters south and east of the Mississippi delta about five miles offshore.
The leak from the ocean floor proved to be far bigger than initially reported, contributing to a growing sense among many in Louisiana that the government failed them again, just as it did during Hurricane Katrina.
President Barack Obama dispatched Cabinet officials to deal with the crisis.
Cade Thomas, a fishing guide in Venice, worried that his livelihood will be destroyed. He said he did not know whether to blame the coastguard, the government or BP.
"They lied to us. They came out and said it was leaking 1,000 barrels when I think they knew it was more. And they weren't pro-active," he said.
"As soon as it blew up, they should have started wrapping it with booms."
The US Coast Guard worked with BP to deploy floating booms, skimmers and chemical dispersants, and set controlled fires to burn the oil off the water's surface.
The coastguard urged the company to request more resources from the US Defence Department. A BP executive said the corporation would "take help from anyone".
Government officials said the blown-out well 40 miles offshore was spewing five times as much oil into the water as originally estimated - about 5,000 barrels, or 200,000 gallons a day.
At that rate, the spill could eclipse the worst oil spill in US history - the 11 million gallons that leaked from the grounded tanker Exxon Valdez in Alaska's Prince William Sound in 1989 - in the three months it could take to drill a relief well and plug the gushing well 5,000 feet underwater on the sea bed.
Ultimately, the spill could grow much larger than the Valdez because Gulf of Mexico wells typically hold many times more oil than a single tanker.
Doug Suttles, chief operating officer for BP Exploration and Production, had initially disputed the government's larger estimate. But he later acknowledged on NBC's 'Today' show that the leak may be as bad as officials said.
He said there was no way to measure the flow at the sea bed, so estimates have to come from how much oil rises to the surface.
Mike Brewer, 40, who lost his oil spill response company in the devastation of Hurricane Katrina nearly five years ago, said he feared the scale of the escaping oil was beyond the capacity of existing resources.
"You're pumping out a massive amount of oil. There is no way to stop it," he said.
An emergency shrimping season was opened to allow shrimpers to scoop up their catch before it was fouled by oil.
Louisiana governor Bobby Jindal declared a state of emergency yesterday so officials could begin preparing for the oil's impact. He said at least 10 wildlife management areas and refuges in his state and neighbouring Mississippi were in the oil plume's path.
The declaration also noted that billions of dollars had been invested in coastal restoration projects that may be at risk and he also asked the government if he could call up 6,000 National Guard troops to help.
The coastguard abandoned a plan on Wednesday to set fire to the leaking oil after sea conditions deteriorated.
The attempt to burn some of the oil came after crews operating submersible robots failed to activate a shut-off device that would halt the flow of oil.
Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, was briefed on the issue, said his spokesman, Captain John Kirby.
But Capt Kirby said the Defence Department had received no request for help, nor was it doing any detailed planning for a mission on the oil spill.
Mr Obama dispatched homeland security secretary Janet Napolitano, interior secretary Ken Salazar and Environmental Protection Agency administrator Lisa Jackson to help with the spill.
He said the White House would use "every single available resource" to respond.
Mr Obama has directed officials to aggressively confront the spill, but the cost of the clean-up will fall on BP, White House spokesman Nick Shapiro said.