DEER PARK, Texas (KTRK) -- Authorities have confirmed that two people died and at least 35 were injured after a chemical leak at a Pemex facility on Thursday evening.

Officials with the Pemex facility at 5900 Highway 225 told ABC13 at about 6:18 p.m. that they were "dealing with an emergency" that began at 4:40 p.m., according to a statement issued hours later.

The chemical, hydrogen sulfide, is a colorless gas known for its pungent "rotten egg" odor at low concentrations. It is extremely flammable and highly toxic and can cause mild headaches, eye irritation, unconsciousness, and death-- even at low concentrations.

In a press conference Thursday night, Sheriff Ed Gonzalez said authorities are working to learn if there are any more deaths.

Eyewitness News saw several ambulances responding and two Life Flight helicopters on standby. SkyEye was over the active scene while Harris County Hazmat Response crews were at work.

Pasadena and Deer Park officials lifted the city shelter-in-place orders after Harris County Pollution Control completed air monitoring in the area and no longer detected hazardous chemicals in the air.

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Harris County Judge Lina Hidalgo shared the following statement:

"I'm aware of the chemical leak at the Pemex plant in Deer Park. At this time there are reports of at least one fatality and multiple injuries at the plant, and my heart goes out to their families and loved ones. The Harris County Fire Marshal's Office and Harris County Pollution Control Services are on scene to assist and monitor the air. Our Office of Homeland Security & Emergency Management is standing by for any additional help that is requested. Our primary concern is to ensure the leak has stopped and that the leaked materials are not impacting county residents. We will send more updates as we get them."

Pemex is a refinery that processes crudes from several countries. They produce a range of products including gasoline, aviation fuel, diesel fuel, and ship fuel.

An hour and a half after reporting the emergency, Pemex officials released the following statement:

"PEMEX Deer Park confirms that a gas release was reported at one of our operating units at 4:40 p.m. The incident is contained to our site and has been isolated. Members of our Emergency Response Team, Channel Industrial Mutual Aid (CIMA) and Harris County Emergency Management personnel and other government agencies are on site and responding to the situation.

Our primary concerns are to ensure the safety of everyone involved and to secure the facility. Out of an abundance of caution, State Highway 225 has been temporarily closed. Some members of the community may see flaring as we safely contain the situation. We are closely monitoring air quality and are not detecting any offsite impacts. We have no additional details at this time. We will provide an update when more information becomes known."

Visit Pamex's website to read the company's Spanish statement about the chemical release.

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