At least two dead and several injured when hydrogen sulfide leaks at the Pemex plant in Texas

Deer Park, Texas — At least two workers at a Houston-area oil refinery died Thursday when hydrogen sulfide leaked from the plant, prompting an urgent warning for residents to stay indoors before authorities later determined there was no danger to the public.

Nearly three dozen other people were either transported to hospitals or treated at the scene, Harris County Sheriff Ed Gonzalez said. Hours after the leak began, Gonzalez said the area was still not safe for investigators and that officers might not be able to get in until Friday.

The facility is operated by Pemex, Mexico’s state-owned oil company, and is located in the suburb of Deer Park.

Gonzalez said the gas release occurred during work on a flange at the plant, part of a collection of oil refineries and plants that make Houston the country’s petrochemical heartland.

Pemex said in a statement that investigations were ongoing and that operations at two units had been “proactively halted” to mitigate the impact.

Local officials issued a shelter-in-place order but lifted it hours later after aerial monitoring showed no threat to the surrounding community, Deer Park Mayor Jerry Mouton said.

Chief meteorologist for CBS Houston affiliate KHOU-TV David Paul said winds were calm Thursday evening.

Hydrogen sulfide is a foul-smelling gas that can be toxic in high concentrations.

“Other than the smell, we had no detectable air monitoring to indicate that anything came out of the facility,” Mouton said.

Television news crews showed several ambulances and emergency vehicles at the scene. Gonzalez originally posted on the social platform

The leak led to the second shelter in Deer Park within weeks. Last month, a Pipeline fire that burned for four days forced surrounding neighborhoods to evacuate.