U.S. Coast Guard Capt. Ed Cubanski said 22 company employees were on the rig when the fire began. He said a pipe -- 3 inches in diameter, 7 feet long and containing about 28 gallons of oil -- apparently ignited while being cut with a torch. He said 11 people were transported to four area hospitals and nine were evacuated uninjured.
Authorities reported earlier that two people had been killed, but at a noon press conference in New Orleans the Coast Guard said there were no confirmed deaths.
The fire began Friday morning, said Kirk Trascher, spokesman for the oil rig's owner, Black Elk Energy of Houston.
The platform is considered non-producing, meaning it is not currently pumping oil, and the incident will likely not devolve into a major oil spill, The (New Orleans) Times-Picayune reported Friday.
The Coast Guard said the rig is in shallow water in West Delta Block 32 of the Gulf of Mexico, about 25 miles southeast of Grand Isle, La.
Workers were performing "shutdown platform work" when the fire began, the Louisiana Governor's Office of Homeland Security and Emergency Preparedness said.
The Coast Guard activated a command center to investigate the incident, and two Coast Guard helicopter teams, from Mobile, Ala. and from New Orleans, were called in to help in the search for the missing workers, KHOU-TV, Houston, reported.
A light oil sheen on the surface of the water, about a half-mile long and 200 yards wide, was visible on the Gulf, which Cubanski said was consistent with the reported 28-gallon spill.