By David Alire Garcia and Erwin Seba
MEXICO CITY/HOUSTON (Reuters) -U.S. and Mexican investigators have begun probes of a fatal chemical leak at a Houston area oil refinery on Thursday owned by Mexico's state oil firm Pemex, officials said on Friday.
Two contract workers were killed and up to 35 others treated for exposure to hydrogen sulfide gas during work on a unit at the 312,500-barrel-per-day (bpd) refinery located near Houston. Thirteen workers remained hospitalized, Pemex said.
Pemex, as Petroleos Mexicanos is best known, launched an investigation into what caused the leak, the company's chief executive said.
The U.S. Chemical Safety and Hazard Investigation Board (CSB), which investigates industrial accidents and makes recommendations to prevent future incidents, also has begun a probe of the "very serious incident," it said.
Pemex Chief Executive Officer Victor Rodriguez told a media briefing that the bodies of two workers were recovered early on Friday morning after the toxic gas had dissipated enough to allow emergency workers to approach the affected area.
"The deceased are not Pemex workers, nor are any of those affected," said Rodriguez, who noted it remains unclear what caused the chemical release.
The fatalities were externally-contracted maintenance workers at the refinery, Rodriguez said. He did not disclose the contractor that employed them.
Work was underway on a sulfur recovery unit at the time, according to people familiar with the matter.
Pemex took full ownership of the Deer Park refinery in early 2022, acquiring Shell (LON:SHEL)'s stake in a refining joint venture. Mexico had acquired the facility to become more self-sufficient in gasoline and diesel.
The CEO, who took over earlier this month, said three or four units were shut at the refinery. Pemex aims to determine the root cause of this incident and the actions that will allow the processing units involved to be restored to operation as soon as possible, it said.
In 2021, Shell disclosed the agreement to sell its interest in Deer Park to its former partner Pemex for some $596 million.
Pemex's domestic refineries have for years suffered a series of accidents, including explosions and fires, that have caused deaths in Mexico.