New Orleans (AP) - As hope dimmed for the lives of 11 crew members missing since a drilling rig exploded in flames in the Gulf of Mexico, authorities turned their focus to controlling an oil spill that could threaten the fragile ecosystem of the Louisiana and Mississippi coasts.
The Deepwater Horizon had burned violently for nearly two days until it sank Thursday morning. The fire's out, but as much as 336,000 gallons of crude oil a day could be rising from the sea floor 5,000 feet below, officials said.
"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.
BP Chief Executive Tony Hayward said the company will do "everything in our power to contain this oil spill and resolve the situation as rapidly, safely and effectively as possible." He says the company can call on more resources if needed.
Ed Overton, an LSU 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, though others were praying for a different outcome. Most of the crew -- 111 members -- were ashore, including 17 taken to hospitals. Four were in critical condition.
The accident shows that drilling is not safe, said Abe Powell, who heads Get Oil Out!, created after a 1969 platform accident off Santa Barbara, Calif., fouled miles of ocean and beaches with wildlife-killing goo and spawned the environmental movement.
"When oil companies say drilling is safe now and we won't allow any accidents ... we know that's not true," he said.
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 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.
Coast Guard Rear Adm. Mary Landry said crews saw a 1-mile-by-5-mile rainbow sheen of what appeared to be a crude oil mix on the surface. There wasn't any evidence crude was coming out after the rig sank, she said, but officials weren't sure what was going on underwater.
At the worst-case figure of 336,000 gallons a day, it would take more than a month for the amount of crude oil spilled to equal the 11 million gallons spilled from the Exxon Valdez in Alaska's Prince William Sound.
A turn in winds and currents might send oil toward fragile coastal wetlands -- nurseries for fish and shrimp and habitat for birds.
"As you get closer to shore, you get richer and richer marine habitats, and also get the potential for long-term exposure," Helton said.
Animals at sea will be briefly exposed to the oil when the slick passes over, but when it hits land, it sticks, he said.
To prevent that, 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 500,000 feet -- 94.6 miles -- of containment boom.
Another 500,000 feet 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 6,000 feet, about 1.1 mile, of boom was in the water by Thursday evening.
While this was happening on the surface, robots tethered to ships nearly a mile above the sea floor sent back video of the damage so crews can decide whether a shutoff valve called a blowout preventer can be closed.
Authorities don't know whether the rig sank to the bottom -- or, if it did, whether it hit the blowout preventer, Lt. Cdr. Cheri Ben-Iesau said.
"It didn't sink catastrophically. It kind of settled into the water" and may still have some buoyancy, she said.
If the valve is too badly damaged to cut off the flow of oil, a nearby rig a safe distance from the broken well will drill a new hole intersecting the one that blew wild. Then heavy fluid called "kill fluid" will be pumped in to plug it, said Scott D. Dean, a BP spokesman.
In addition to other environmental concerns, the well is in an area where a pod of sperm whales is known to feed, said Kim Amendola of NOAA. Sarthou said she was worried the activity around the well might disturb the whales.
Meanwhile, relatives of the missing waited for news.
Carolyn Kemp of Monterey, La., said her grandson, Roy Wyatt Kemp, 27, would have been on the drilling platform when it exploded.
"They're assuming all those men who were on the platform are dead," Kemp said. "That's the last we've heard."
Jed Kersey, of Leesville, La., said his 33-year-old son, John, had finished his shift on the rig floor and was sleeping. He said his son told him all 11 missing workers were on the rig floor at the time of the explosion.
"He said it was like a war zone," said Jed Kersey, a former offshore oil worker.
The family of Dewey Revette, a 48-year-old from southeast Mississippi, said he worked as a driller on the rig and had been with the company for 29 years.
"We're all just sitting around waiting for the phone to ring and hoping for good news. And praying about it," said Revette's 23-year-old daughter, Andrea Cochran.
Those who escaped did so mainly by getting on lifeboats that were lowered into the Gulf, said Adrian Rose, vice president of Transocean.
Weekly emergency drills seemed to help, he said, adding that workers apparently stuck together as they fled the blast.
"There are a number of uncorroborated stories, a lot of them really quite heroic stories, of how people looked after each other. There was very little panic," Rose said.
Family members of two missing workers filed separate lawsuits Thursday accusing Transocean and BP of negligence. Both companies declined to comment about legal action against them after the first suit was filed.
The U.S. Minerals Management Service, which regulates oil rigs, conducted three routine inspections of the Deepwater Horizon this year -- in February, March and on April 1 -- and found no violations, MMS spokeswoman Eileen Angelico said.
Associated Press Writer Noaki Schwartz reported from Los Angeles, Holbrook Mohr from Jackson, Miss., Mike Kunzelman, Cain Burdeau and Alan Sayre in Louisiana, Chris Kahn in New York and Sofia Mannos of AP Television News contributed to this report.
The Deepwater Horizon oil rig sank Thursday morning, creating a huge oil spill. Officials say as much 336,000 gallons of crude oil a day could be rising from the sea floor 5,000 feet below.