Chief Petty Officer Bobby Nash told The Associated Press that the search was ended at about 5:25 p.m. CST Saturday. Helicopters had been searching for the missing workers from the air, while a cutter searched the sea.
The blaze erupted Friday as workers were using a torch to cut an oil line on a platform owned by Houston-based Black Elk Energy about 20 miles (40 kilometers) southeast of Grand Isle, La.
Four workers were severely burned, though Black Elk Energy spokeswoman Leslie Hoffman said their burns were not as extensive as initially feared.
Officials at Baton Rouge General Medical Center said Saturday that two men remained in critical condition, while two men remained in serious condition. The four, being treated in a burn unit, are employees of oilfield contractor Grand Isle Shipyard and are from the Philippines. The hospital said it and Grand Isle Shipyard are trying to reach the men's families in the Philippines.
It's unclear whether the missing men worked for a contractor. Grand Isle Shipyard employed 14 of the 22 workers on the platform at the time of the incident, WWL-TV in New Orleans reported. A man who answered the phone at the company's Galliano, La., office on Saturday said no one was available to comment.
Meanwhile, officials said no oil was leaking from the charred platform, a relief for Gulf Coast residents still weary two years after the BP oil spill illustrated the risk that offshore drilling poses to the region's ecosystem and economy.
Friday's fire sent an ominous black plume of smoke into the air reminiscent of the deadly 2010 Deepwater Horizon explosion that transformed the oil industry and life along the U.S. Gulf Coast.
James A. Watson, the director of Louisiana's Bureau of Safety and Environmental Enforcement, said in a statement Saturday that his agency had begun "an investigation into the explosion and fire aboard a Black Elk Energy production platform offshore Louisiana."
"Our thoughts and prayers are with those injured and missing and their families," Watson said. "BSEE is committed to determining the direct and indirect causes of the explosion and will take appropriate enforcement action."
The Deepwater Horizon blaze killed 11 workers and led to an oil spill that took months to bring under control. Friday's fire came a day after BP PLC agreed to plead guilty to a raft of charges in the 2010 spill and pay a record $4.5 billion in penalties.
There were a few important differences between this latest blaze and the one that touched off the worst offshore spill in U.S. history: Friday's fire was put out within hours, while the Deepwater Horizon burned for more than a day, collapsed and sank.
The Black Elk Energy facility is a production platform in shallow water, rather than an exploratory drilling rig like the Deepwater Horizon looking for new oil on the seafloor almost a mile (1.6 kilometers) deep.
The depth of the 2010 well blow-out proved to be a major challenge in bringing the disaster under control.
The Black Elk platform is in 56 feet (17 meters) of water - a depth much easier for engineers to manage if a spill had happened.
A sheen of oil about a half-mile (800 meters) long and 200 yards (180 meters) wide was reported on the Gulf surface, but officials believe it came from residual oil on the platform.
"It's not going to be an uncontrolled discharge from everything we're getting right now," Coast Guard Capt. Ed Cubanski said.
Hoffman, the Black Elk Energy spokeswoman, said Saturday that there were still no signs of any leak or spill at the platform site.
BP's blown-out well spewed millions of gallons (liters) of oil into the sea, about 50 miles (80 kilometers) southeast of the mouth of the Mississippi River on the east side of the river delta. The crude fouled beaches, marshes and rich seafood grounds.
After Friday's blaze, 11 people were taken by helicopter to area hospitals or for treatment on shore by emergency medical workers.
The production platform is on the western side of the Mississippi River delta. The Coast Guard said 24 people were aboard the platform at the time of the fire.
"The company continues to cooperate closely with all state and federal agencies," company officials said in a news release Saturday. "As reported yesterday, this platform was not in operation and had been shut in since mid-August. According to visual reports from this morning, there is no visible sheen in the vicinity of the platform."
Cubanski said the platform appeared to be structurally sound. He said only about 28 gallons (106 liters) of oil were in the broken line on the platform.
David Smith, a spokesman for the Interior Department's Bureau of Safety and Environmental Enforcement in Washington, said an environmental enforcement team was dispatched from a Gulf Coast base by helicopter soon after the Coast Guard was notified of the emergency. Smith said the team would scan for any evidence of oil spilling and investigate the cause of the explosion.
Black Elk is an independent oil and gas company. The company's website says it holds interests in properties in Texas and Louisiana waters, including 854 wells on 155 platforms.
John Hoffman, Black Elk's president and CEO, said in an email early Saturday morning that he was leaving Houston for Louisiana to assist in the investigation and help the families of the missing and injured workers.
"My entire focus is the families and workers," he wrote. "Nothing else matters at this point."