NEW ORLEANS -- Workers in Louisiana were trying to contain oil spilled from a rig explosion and prevent any threat to the coast's fragile ecosystem, as the search continued Friday for the 11 workers who were still missing.
No more oil appeared to be leaking from the well head on the ocean floor after the drilling rig exploded and sank in the Gulf of Mexico, the Coast Guard said Friday.
The rig burned for nearly two days until it sank Thursday morning. The fire was out, but officials initially feared as much as 336,000 gallons (1.27 million liters) of crude oil a day could be rising from the sea floor nearly 5,000 feet (1,524 meters) below.
Coast Guard Rear Adm. Mary Landry said crews were closely monitoring the rig for any more crude that might spill out.
The crew was finishing the well about 50 miles (80 kilometers) off the Louisiana coast when the rig exploded. Officials have not said what caused the blast, and the oil they are dealing with now is left over from the explosion and sinking.
"If it gets landward, it could be a disaster in the making," said Cynthia Sarthou, executive director for the environmental group Gulf Restoration Network.
BP PLC, which leased the rig and took the lead in the cleanup, said Friday it has "activated an extensive oil spill response," including using remotely operated vehicles to assess the subsea well and 32 vessels to mop up the spill.
Ed Overton, a Louisiana State University environmental sciences professor, said he expects some of the light crude oil to evaporate while much of it turns into a pasty mess called a "chocolate mousse" that ultimately breaks apart into "tar balls," small chunks of oily residue that can wash ashore.
"It's going to be a god-awful mess for a while," he said. "I'm not crying doomsday or saying the sky is falling, but that is the potential."
The Coast Guard early Friday was searching for the missing, but some family members said they had been told that officials assumed all were dead. Most of the crew -- 111 members -- were ashore, including 17 taken to hospitals. Four were in critical condition.
Lt. Cmdr. Cheri Ben-Iesau said a Coast Guard cutter would remain on the scene Friday after searching overnight, and a helicopter would take advantage of clear weather to make three more search flights Friday.
Ben-Iesau said a rainbow sheen of what appeared to be a crude oil mix on the surface had expanded to 10 miles by 10 miles (16 kilometers by 16 kilometers) as of Friday morning.
Weather forecasts indicate the spill was likely to stay well away from shore at least through the weekend, but if winds change it could come ashore more rapidly, said Doug Helton of the National Oceanographic and Atmospheric Administration's office of response and restoration.
The Coast Guard, which was leading the investigation, hadn't given up the search early Friday for those missing from the rig, which went up in flames Tuesday night about 41 miles (66 kilometers) from the mouth of the Mississippi River.
Four who made it off safely were still on a boat operating one of several underwater robots being used to assess whether the flow of oil could be shut off at a control valve on the sea floor, said Guy Cantwell, spokesman for rig owner Transocean Ltd.
The Marine Spill Response Corp., an energy industry cleanup consortium, brought seven skimmer boats to suck oily water from the surface, four planes that can scatter chemicals to disperse oil, and 94.6 miles (152 kilometers) of containment boom, a floating barrier with a skirt that drapes down under the water and corrals the oil.
Another 500,000 feet (152,400 meters) of boom were on the way, BP spokesman Tom Mueller.
"Right now we are over-responding with resources to manage the potential spill here," he said. "We will be well-prepared to manage whatever comes."
He said about 1.1 mile (1.8 kilometer) of boom was in the water by Thursday evening.
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