Mexican President Felipe Calderon has ordered an inquiry after an accident on an offshore oil platform in the Gulf of Mexico left at least 19 people dead.
Some survivors had harrowing tales to tell
Huge waves knocked the platform onto its side and into a drilling rig, setting off gas and oil leaks.
Desperate workers scrambled into life rafts to escape.
More than 60 survivors were rescued, some after hours in the water, but the search is continuing for four workers missing since the accident on Tuesday.
The accident on the Usumacinta platform happened during a heavy storm.
There were wind gusts of up to 130km/h (80mph) and waves of up to eight metres (26ft) at the time of the collision, Mexico's state oil company, Pemex, said.
Most of the victims drowned when their rafts were swamped in high seas.
One survivor told Mexico's Televisa network that they only abandoned the platform after the leaking gas became unbearable and they had no air left in their emergency breathing devices.
The platform involved in the accident was similar to this one
Their lifeboat began to break up, Eder Ortega said, "little by little, until the raft finally went under and all my colleagues ended up in the water".
"All night long I was alone at sea," said Jesus Manuel Garcia, who was rescued after drifting for 16 hours.
"I saw a lot of my colleagues floating around... Thank God I get a second chance."
President Calderon, who visited some of the survivors on Thursday, instructed Pemex officials to carry out a thorough investigation into the accident.
The platform, which is fixed to the sea bed, should be able to withstand gale-force winds.
Questions are also being raised about the state of the lifeboats, the Associated Press reported.
Pemex said it would take several days to control the leaks but that the spill of crude oil was less than originally thought.