A toxic hydrogen sulfide leak at Pemex's Deer Park oil refinery resulted in two fatalities and prompted a shelter-in-place order for nearby residents on Wednesday afternoon, as investigations into the cause begin.

The hydrogen sulfide leak, which occurred during contractor work on a sulfur recovery unit, led to the evacuation of local residents and left 35 individuals requiring medical treatment for exposure. The incident has raised serious safety concerns about refinery operations and the potential environmental impact, with investigations currently underway to determine the precise cause of the leak.

At approximately 4:40 p.m. local time, the leak was reported, indicating a critical failure in safety protocols during contractor work. Emergency crews rapidly responded to the scene, and air monitoring was initiated to assess the exposure levels of the toxic gas. Officials stated that hydrogen sulfide is particularly hazardous due to its characteristic rotten egg odor and can pose severe health risks even at low concentrations.

In light of the situation, a shelter-in-place order was enacted for the communities of Deer Park and Pasadena. This precaution advised residents to remain indoors, turn off air conditioning units, and minimize outdoor activity to avoid inhaling the dangerous gas. The shelter-in-place order was subsequently lifted once the situation was deemed safe, although the investigation continued indefinitely.

Overall, 35 individuals at the refinery received treatment for symptoms associated with hydrogen sulfide exposure. The health and safety of workers and nearby residents became a significant concern for authorities. The two fatalities were confirmed to be refinery workers who were present during the incident. Their identities have not been released pending notification of their families.

Pemex, the state-owned petroleum company of Mexico, took swift action in response to the leak. The company announced that operations were halted at two refining units in the facility. Officials from Pemex expressed their commitment to reviewing safety protocols and implementing necessary changes to prevent such incidents in the future.

The Deer Park facility is a considerable site for Pemex, processing crude oil into various fuel products. It plays a crucial role in the supply of refined petroleum products in the region. Given the severity of the leak, there are ongoing concerns about the impact of such incidents on local air quality and public health, as well as the facility's operational integrity.

The investigation into the cause of the leak is currently underway, with local sheriff's officials suggesting it may take several hours before investigators can safely enter the affected area to gather information. Sheriff's deputies are coordinating with the Texas Commission on Environmental Quality and other agencies to assess the situation and ensure public safety.

Incidents of hydrogen sulfide leaks in oil and gas facilities continue to highlight the need for stringent safety measures and regulatory oversight. As the investigation unfolds, further details about the protocol adherence at the refinery will be scrutinized, and the results could prompt broader discussions on the safety of refinery operations across the industry.