A helicopter carrying oil company workers crashed in the Gulf of Mexico off Lake Charles, La., early Friday, and four people were missing and believed dead, officials said. Two other passengers were rescued by a workboat. A search was under way for the missing after the helicopter went down near an oil rig about 120 miles south of Cameron, Mobil Oil Exploration & Producing Southeast said in a statement. The two rescued men were in serious condition at St. Patrick's Hospital with leg and chest injuries, said spokeswoman Debbie Serra. Michael O'Malley, a Mobil spokesman in Dallas, said four passengers were Mobil employees and one was a welder.