DEER PARK, Texas (KTRK) -- Crews continued their response to the Shell Deer Park facility fire late Friday night as the once-raging flames died down into the evening.
The company said all workers on site were accounted for, including nine contractors who were evaluated at a hospital and later released.
The fire broke out at about 3 p.m. at 5900 State Highway 225, according to Shell. Heavy smoke was seen from miles away as SkyEye flew over the plant.
Authorities initially said some type of "explosion" unfolded at the plant, but later corrected it to only a fire emergency.
"Kind of a boom and more like a roaring sound," Trevor Jones, who lives nearby, said.
Deer Park Mayor Jerry Mouton told ABC13 over the phone that this was an oil and gas fire from a leak, and that what was burning was "burnt carbon," which he said is safe for the community.
At an evening news conference, officials described the chemical released as a "hydrocarbon," which they say is a heavy gas oil and precursor to the production of gas and diesel.
"At approximately 2:56 PM CST a fire started at Shell's Deer Park Chemicals facility in the olefins unit. The ignited product includes cracked heavy gas oil, cracked light gas oil and gasoline. No injuries have been reported, though a small number of contract employees who were exposed to product are undergoing medical evaluation as a precaution," Shell said in a statement, in part, regarding Friday's incident.
The Harris County Sheriff's Office said five contractors were transported to the hospital for precautionary reasons, largely due to the heat. Officials added three more people to that count after they self-transported to Memorial Hermann Southeast. By late Friday, Shell added one more person to those treated.
However, a father at the hospital told ABC13 his son looked burned.
"His face is red hot. The oil and steam splashed him," Pablo Jasso, whose son was admitted, said.
Deputies said routine maintenance to a heat exchanger was happening at the time of the incident. Video shared with ABC13 from inside the facility showed workers jumping a fence to escape the fire.
As the fire burned, at least three stacks flared to relieve pressure, HCSO added.
HCSO said the fire was diminishing and contained, saying the product was being depressurized and visible flares were there to relieve pressure.
"These things are always scary when they initially happen," Sheriff Ed Gonzalez said, adding the fire was always contained to one unit.
WATCH: Harris Co. officials offer first public words after Deer Park plant fire
Despite the emergency response, Deer Park ISD and city officials said there was no shelter in place due to the wind blowing away from the city, adding that air monitoring is being conducted in the area.
The district said the incident did not affect school dismissal for its students, who were let out for the day as normal.
The Texas Commission on Environmental Quality and multiple fire department agencies, including those from Deer Park, Houston, Harris County, and PEMEX, responded to the fire. The Harris County Pollution Control Services Department activated an air monitoring portal in the wake of the emergency.
Shell insisted there's no threat to the community and that no harmful chemical levels were detected.
Harris County Precinct 2 Commissioner Adrian Garcia added that all of the employees at the facility were accounted for and issued the following statement:
"My office has been in touch with the Office of Emergency Management, and we have also personally spoken with the plant manager at the facility that has been burning. In addition, the Fire Marshal and Harris County Pollution Control are on site, and we've been assured that the situation is under control. All employees at the facility have been accounted for. We urge people to avoid the area to make room for emergency response. There is no shelter-in-place currently in effect.
Our CAMP (Community Air Monitoring Program) dashboard is operational, and we expect air quality data to start rolling in shortly. Houston Advanced Research Center (HARC) will provide additional guidance on air quality as needed. As we learn more, we will be sure to share those updates.
We don't know the cause of the fire, but a Harris County Fire Marshal investigation will begin as soon as the fire is out. Pollution Control will also remain in the area to continue air monitoring in the days ahead."