The helicopter went down near a marshy area near Houma around 3 p.m. Sunday, according to The Times-Picayune of New Orleans.
Petty Officer Jaclyn Young told the Times-Picayune the Coast Guard assisted Terrebonne Parish law enforcement in searching for and recovering the bodies of the dead and rescuing the survivor. No details were available on the condition of the survivor who was taken to a hospital in Houma.
The helicopter is owned by PHI Inc., a Lafayette-based company that serves the energy industry and flies medical helicopters. The cause of the crash isn't known.
PHI spokesman Richard Ravinelli said the helicopter had just taken off from the company's base in Amelia and was heading to an offshore oil platform when it crashed.
Ravinelli said the names of the victims would released after next of kin are notified.
Houma Today reported that the chopper crashed in a marshy area near Bayou Penchant that was only accessible by airboat, hindering recovery efforts.
In June, a PHI Air Medical helicopter crashed in Texas, killing four. The accident in the Sam Houston National Forest killed the pilot, paramedic, nurse and a patient who was being transported from Huntsville to Houston. That crew agreed to transport the patient after another helicopter company abandoned the mission saying that cloud cover was too low, making visibility poor in the early-morning darkness.