A supply boat on the scene rescued seven people, and five were transported to the University Medical Center in New Orleans.
The Clovelly Oil Co. platform exploded Sunday night while maintenance was being done on the structure, sending a fireball high into the night sky, authorities and company officials said.
Chief David Tibbets of the East Bank Consolidated Fire Department says the platform, located in Jefferson Parish, is used for the transfer of oil.
Huge Oil Rig #Explosion as Republicans continue to remove every regulation they can lay their hands on. Two other people were taken to a hospital in Metairie and discharged overnight.
A statement from Clovelly Oil said three oil wells near the platform were shut in at the time of the explosion and its one gas well was flowing, but was successfully shut-in shortly after the explosion.
Jefferson Parish's water supply comes from the Mississippi River and no drinking water comes from Lake Pontchartrain, Yenni said.
Several residents in Kenner told WWL-TV that they heard a loud boom that caused their homes to shake Sunday night.
No other rigs on the lake were at risk of igniting, according to authorities. The Coast Guard said there was no sign of pollution in the lake.
Officials say the platform is about a mile and a half from the Kenner Boat Launch.
Local authorities are performing a search and rescue for one person still unaccounted for after an oil rig explosion on Lake Pontchartrain. The state Louisiana Department of Wildlife and Fisheries, Jefferson Parish Sheriff's Office, St. Charles Parish Sheriff's Office and Bayou Gauche Fire Department also responded. He also confirmed that there was some cleaning being done on the platform, but did not specify the exact cause for the explosion.