The New Orleans Coast Guard began searching Wednesday afternoon for people aboard a civilian helicopter that went down earlier in the day about 60 miles south of Terrebonne Bay.
Two people aboard the chopper were able to deploy a life raft and escape the rig before it sank, said Coast Guard officials who began the rescue effort after hearing from them.
The cause of the chopper going into the water is unclear.
Vessels aiding in the search include a MH-65 Dolphin helicopter, a HC-130 Ocean Sentry fixed-wing aircraft and the Coast Guard Cutter Sturgeon, an 87-foot patrol boat, officials said.
Two civilian boats are also helping in the search.
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