NEW ORLEANS (AP) — An explosion rocked an offshore oil drilling platform, sending a column of fire into the sky and touching off a frantic search at sea Wednesday for at least 11 reported missing.
Most of the 126 workers on the rig Deepwater Horizon were believed to have escaped safely after the explosion about 10 p.m. Tuesday, Coast Guard Senior Chief Petty Officer Mike O'Berry said.
The rig, more than 50 miles southeast of Venice on Louisiana's tip, was still burning Wednesday morning and was listing about 10 degrees. There was no estimate of when the flames might be out.
Helicopters and boats searched the Gulf of Mexico for any sign of the workers who had not been accounted for.
"We're hoping everyone's in a life raft," O'Berry said.
The Coast Guard said Wednesday that seven workers had been critically injured. Later in the day, West Jefferson Hospital in suburban New Orleans said it treated four people, three of whom had been released. The University of South Alabama Medical Center said it was treating one person in its burn unit and evaluating five others.
O'Berry said many workers who escaped were being brought to land on a work boat expected to arrive Wednesday evening.
When the explosion happened, the rig was drilling but was not in production, according to Greg Panagos, spokesman for its owner, Transocean Ltd. in Houston. The rig was under contract to BP PLC. BP spokesman Darren Beaudo said all BP personnel were safe but he didn't know how many BP workers had been on the rig.
Panagos said it's still too early to know what caused the explosion.
"Our focus right now is on taking care of the people," he said.
O'Berry said Coast Guard environmental teams were on standby in Morgan City, La., to assess any environmental damage once the fire was out.
According to Transocean's website, the Deepwater Horizon is 396 feet long and 256 feet wide. The semi-submersible rig was built in 2001 by Hyundai Heavy Industries Shipyard in South Korea. The site is known as the Macondo prospect, in 5,000 feet of water.
The rig is designed to operate in water up to 8,000 feet deep and has a maximum drill depth of about 5.5 miles. It can accommodate a crew of up to 130.
A semi-submersible rig is floated to a drilling site. It has pontoons and a column that submerge when flooded with seawater. The rig doesn't touch the sea floor, but sits low in the water, where it is moored by several large anchors.
Last September, the Deepwater Horizon set a world deepwater record when it drilled down just over 35,000 feet at another BP site in the Gulf of Mexico, Panagos said.
"It's one of the more advanced rigs out there," he said.
Panagos did not know how much the rig cost to build, but said a similar rig today would run $600 million to $700 million.
Transocean has 14 rigs working in the Gulf and 140 worldwide.
Associated Press Writers Alan Sayre in New Orleans and Cain Burdeau in Port Fourchon, La., contributed to this report.
Copyright 2010 The Associated Press.