An explosion of an oil rig in U.S. state of Louisiana left at least 11 workers missing, and search and rescue teams are looking for them, authorities said Wednesday.

The explosion happened late Tuesday night at the Deepwater Horizon rig in Gulf of Mexico, and most of the 126 workers on site were believed to have escaped safely.

The rig is located at about 82 km southeast of Venice, Louisiana. Local media quoted Coast Guard Senior Chief Petty Officer Mike O'Berry as saying the fire is still burning. Seven workers were badly hurt.

O'Berry said authorities are still searching the Gulf of Mexico for any signs of lifeboats. Helicopters, ships and an airplanes were deployed for the search and rescue mission.

Built in 2001, the rig was owned by Transocean Ltd., and was under contract to BP PLC. It was drilling but was not in production.