Mexico City – A huge blaze twisted and blackened an oil platform in the Gulf of Mexico last week, but the state-run Petróleos Mexicanos (Pemex) oil company said it managed to avert any significant oil spill.

Officials said environmental damage was avoided because the fire happened on a processing platform where the feeder lines could be turned off, rather than at an active oil well with a virtually unlimited amount of fuel flowing up from the seabed.

Three workers were reported missing following the blaze that killed 4, injured 16, and forced the evacuation of 300 workers.

Helicopters flew workers with bandaged hands and faces and burn marks on their overalls to nearby Ciudad del Carmen, where crowds of relatives of oil workers thronged outside hospitals. Pemex said a total of 45 workers received medical treatment or evaluation.

A survivor of the blaze on the shallow-water Abkatun-A Permanente platform in the Campeche Sound said workers "jumped into the sea out of desperation and panic."

"There was nothing you could do but run," said Roger Arias Sanchez, an employee of Pemex contractor Cotemar who escaped the burning platform in an evacuation boat.

Many of the injured appeared to be Cotemar employees.

On Thursday, Pemex said it became aware of three missing workers when it recounted personnel. One of the missing workers was from Pemex and the other two were employed by Cotemar, a company statement reported.

Mexican President Enrique Peña Nieto promised an investigation to "find whoever is responsible" and avoid such accidents in the future.

Pemex Director General Emilio Lozoya said the explosion appeared to have been set off by some kind of mechanical problem but the precise cause was still under investigation.