NEW ORLEANS – Rescuers in helicopters and boats searched the Gulf of Mexico for 11 missing workers Wednesday after a thunderous explosion rocked a huge oil drilling platform and lit up the night sky with a pillar of flame. Seventeen people were injured, three critically.

The blast Tuesday night aboard the Deepwater Horizon rig 50 miles off the Louisiana coast could prove to be one of the nation’s deadliest offshore drilling accidents of the past half-century.

The Coast Guard held out hope that the missing workers escaped in one of the platform’s covered lifeboats.

Nearly 24 hours after the explosion, the roughly 400- by 250-foot rig continued to burn, and authorities could not say when the flames might die out. A column of boiling black smoke rose hundreds of feet over the Gulf of Mexico as fireboats shot streams of water at the blaze.

“We’re hoping everyone’s in a life raft,” Coast Guard Senior Chief Petty Officer Mike O’Berry said.

Adrian Rose, vice president of rig owner Transocean Ltd., said the explosion appeared to be a blowout, in which natural gas or oil forces its way up a well pipe and smashes the equipment. But precisely what went wrong was under investigation.

Crews were doing routine work before the explosion and there were no signs of trouble, Rose said.

A total of 126 workers were aboard the rig when it blew up. The Coast Guard said 17 were taken by air or sea to hospitals. Three were in critical condition with severe burns. Others suffered burns, broken legs and smoke inhalation.

Nearly 100 other workers made it aboard a supply boat and were expected to reach the Louisiana shore by evening.

Kelly Eugene waited with nine family members for husband Kevin Eugene, 46, a cook on the Deepwater Horizon.

A catering company operating on the rig notified her he was safe.

“He’s on the boat. That’s all we know,” she said.

“And that’s all we need to know.”

The rig was tilting as much as 10 degrees after the blast, but earlier fears that it might topple over appeared unfounded.

Coast Guard environmental teams were on standby, though officials said the damage to the environment appeared minimal so far.

The rig, which was under contract to the oil giant BP, was doing exploratory drilling but was not in production, Transocean spokesman Greg Panagos said. Seventy-nine Transocean workers, six BP employees and 41 contract workers were aboard.