A series of explosions shook a Mobil Oil Corp. refinery and set off a fire that severely burned an employee, authorities said.

The first explosion occurred about 11:30 p.m. Sunday. The fire continued to burn early Monday but was contained, said Peggy Poche, spokeswoman for the St. Bernard Parish sheriff.The fire erupted in a unit used for gasoline refining, said plant safety manager Jack Cohn. The cause was not immediately known, he said.

Mobil employee John Oler, 38, of Chalmette was hospitalized at Chalmette Medical Center with burns over 70 percent of his body, officials said.