The Coast Guard said no one was killed in the explosion, which was spotted by a commercial helicopter flying over the site Thursday morning. All 13 people aboard the rig have been accounted for, with one injury. The extent of the injury was not known.
They were rescued from the water by an offshore service vessel, the Crystal Clear, said Coast Guard Cmdr. She said they were taken to a nearby platform. All were being flown to the Terrebonne General Medical Center in Houma to be checked over.
"Thirteen people were seen huddled together in the water wearing gumby suits or immersion suits, water protection suits, so we were able to confirm that all people were accounted for," Coast Guard spokesman Chief Petty Officer John Edwards said.
Seven Coast Guard helicopters, two airplanes and three cutters were dispatched to the scene from New Orleans, Houston and Mobile, Ala., Ben-Iesau said. She said authorities do not know whether oil was leaking from the site.
The platform, known as Vermilion Oil Platform 380, was owned by Mariner Energy of Houston, according to a homeland security operations update obtained by The Associated Press. The platform was not producing oil and gas, according to the operations report.
Melissa Schwartz, spokeswoman for Bureau of Energy Management Regulation and Enforcement, said the platform was authorized to produce oil and gas at this water depth but had not been recently in active production.
"There were ongoing maintenance activities underway," she said, adding it was in approximately 340 feet of water.
White House press secretary Robert Gibbs said President Barack Obama was in a national security meeting and did not know whether Obama had been informed of the explosion.
"We obviously have response assets ready for deployment should we receive reports of pollution in the water," Gibbs said.
A call to the company seeking comment was not immediately returned.
Mariner Energy focuses on oil and gas exploration and production in the Gulf of Mexico. In April, Apache Corp., another independent petroleum company, announced plans to buy Mariner in a cash-and-stock deal valued at $3.9 billion, including the assumption of about $1.2 billion of Mariner's debt. That deal is pending.
Apache spokesman Bob Dye said the platform is in shallow water. A company report said the well was drilled in the third quarter of 2008 in 340 feet of water.
Responding to an oil spill in shallow water is much easier than in deep water, where crews depend on remote-operated vehicles access equipment on the sea floor.
The platform is about 200 miles west of BP's blown out Macondo well. On Friday, BP was expected to begin the process of removing the cap and failed blowout preventer, another step toward completion of a relief well that would complete the choke of the well. The BP-leased rig Deepwater Horizon exploded April 20, killing 11 people and setting off a massive oil spill.
Associated Press writers Janet McConnaughey in New Orleans, Chris Kahn in New York and Matthew Daly and Gerry Bodlander in Washington contributed to this report.