An offshore oil rig exploded and caught fire Thursday in the Gulf of Mexico, the US Coast Guard said.

All 13 rig workers abandoning the rig and were floating together near the well when rescued, Coast Guard Captain Peter Troedsson told reporters. The workers were taken to a local hospital for examination, though no one was seriously injured, Troedsson said.

The rig's owner, Mariner Energy, initially reported an oil sheen near the rig about 145 km south of Vermillion Bay on Louisiana's coast, but Throedsson said there was now no evidence that any oil had leaked into the water.

Louisiana Governor Bobby Jindal said earlier that seven wells in the area including the one that exploded have been shut down.

The fire, which was first spotted by workers on a nearby well, had been extinguished by Thursday afternoon, he said. The rig did not sink.

The cause for the explosion was unknown.

A rig explosion in April killed 11 workers and unleased an oil gusher that fouled Gulf waters for months in the biggest-ever marine oil spill in the US.

That accident at a well owned by British oil giant BP had prompted the Obama administration to issue a moratorium on deep-water oil drilling, which was later overturned by a court. The rig involved in Thursday's accident was located in shallower water and would not have fallen under the ban.