"We obviously have response assets ready for deployment, should we receive reports of pollution in the water," Gibbs told a daily briefing.

The offshore oil rig exploded on Thursday, west of the site of the April blast that caused the massive oil spill.

A commercial helicopter company reported the blast around 9:30 a.m. CDT (1430 GMT) Thursday, Coast Guard Petty Officer Casey Ranel said. Seven helicopters, two airplanes and four boats were en route to the site, about 80 miles (130 kilometers) south of Vermilion Bay along the central Louisiana coast.

The Coast Guard said initial reports indicated all 13 crew members from the rig were in the water. One was injured, but there were no deaths.

The platform owned by Mariner Energy is in about 2,500 feet (750 meters) of water, the Coast Guard said, and was not currently producing.

About 206 million gallons (780 million liters) of oil from an undersea well spilled into the Gulf after BP's Deepwater Horizon rig exploded April 20, killing 11 workers.