PENSACOLA — The BP oil slick drifted perilously close to the Florida Panhandle's sugar-white beaches Wednesday as a risky gambit to contain the leak by shearing off the well pipe ran into trouble a mile under the sea when the diamond-tipped saw became stuck.
The saw had sliced through about half of the pipe when it snagged, and it took BP 12 hours to free it. The company said preparations were being made to resume cutting but didn't give a timetable on when it might start.
The plan is to fit a cap on the blown-out well at the bottom of the Gulf of Mexico to capture most of the spewing oil; the twisted, broken pipe must be sliced first to allow a snug fit.
As the slick drifted within 7 miles of Pensacola's beaches, emergency workers rushed to link the last in a miles-long chain of booms designed to fend off the oil. They were slowed by thunderstorms and wind before the weather cleared in the afternoon.
Forecasters said the oil would probably wash up by Friday, threatening a delicate network of islands, bays and white-sand beaches that are a haven for wildlife and a major tourist destination.
"We are doing what we can do, but we cannot change what has happened," said John Dosh, emergency director for Escambia County, which includes Pensacola.
Coast Guard Adm. Thad Allen said more staff, boats and helicopters were sent to the eastern Gulf Coast as the slick spread, including a cutter in Mobile Bay, Ala., and one off Pensacola. The boats will help skim oil and add more booms to collect it. Four helicopters would help skimmers spot threatening oil.
Since the biggest oil spill in U.S. history began to unfold April 20 with an explosion that killed 11 workers aboard an offshore drilling rig, crude oil has fouled some 125 miles of Louisiana coastline and washed up in Alabama and Mississippi as well. Over the past six weeks, the well has leaked anywhere from 21 million to 45 million gallons by the government's estimate.
Officials said the slick sighted offshore consisted in part of "tar mats" about 500 feet by 2,000 feet in size.
In other developments:
• Investors ran from BP's stock for a second day, fearful of the potential cleanup costs, lawsuits, penalties and damage to the company's reputation.
•President Barack Obama said it is time to roll back billions of dollars in tax breaks for oil companies and use the money for clean energy research and development.
• Two Democratic senators pressed BP to delay plans to pay shareholder dividends worth $10 billion or more. They called it "unfathomable" that BP would pay out a dividend before the total cost of the cleanup is known. BP had no comment.
• More fishing grounds were closed. More than a third of federal waters in the gulf are now off-limits to fishing, along with hundreds of square miles of state waters.