VENICE, La. (AP) — An oil rig explosion off the coast of Louisiana sent four people to hospital Friday and two others were believed to be missing, Coast Guard officials said.Coast Guard spokesman Drake Foret said the fire was out in the meantime. Four people were taken to West Jefferson Medical Center near New Orleans and Coast Guard aircraft and boats were searching for two missing people.The rig, a production platform owned by Black Elk Energy, is about 25 miles southeast of Grand Isle, La.The platform is for oil production from an established well, unlike the Deepwater Horizon rig, which was drilling an exploratory well for oil giant BP in mile-deep water when it blew up and triggered a massive oil spill in 2010. That site is well to the east of Friday’s explosion.Local officials said the Coast Guard has told them there was no pollution at the site. Plaquemines Parish spokeswoman Caitlin Campbell said the Coast Guard reported that the platform was intact and suffered no structural damage.Coast Guard Capt. Peter Gautier told WWL TV the platform was not producing oil at the time and no environmental threat was anticipated. Gautier said it was believed that maintenance workers were cutting a pipe and some oil may have gotten loose, causing the fire.