What chemical was released during the ExxonMobil plant fire in Baytown?

BAYTOWN, Texas (KTRK) -- Officials have now identified the chemical released into the air after a fire at the ExxonMobil plant in Baytown Thursday morning.

At about 5:45 a.m. Thursday, emergency response teams were at the scene working to extinguish the fire, according to Exxon. SkyEye captured the video above, showing large amounts of smoke in the area. By 9:15 a.m., Exxon said teams had safely extinguished the fire.

According to reports, the unit that burned was used to make gasoline. A process that includes using the chemical naphtha.

So what exactly is naphtha?

According to the U.S. Energy Information Administration, naphtha is a generic term applied to a refined or partially refined petroleum fraction with an approximate boiling range between 122 degrees and 400 degrees Fahrenheit.

SEE ALSO: 4 people injured in ExxonMobil plant fire in Baytown, officials say

Naphtha can also be used as jet fuel.

In an afternoon update from the Texas Commission on Environmental Quality, all readings were below detection levels with no detectable odors. These results were consistent with those from Harris County and ExxonMobil.

Thursday's fire at the plant left four people injured. Two of the victims were treated for burns, a third victim suffered a fracture and the fourth victim was treated for injuries related to a fall of about 40 feet.

Since then, two of the victims were discharged and two remain in the hospital for further treatment. Both contractors are in stable condition.

ExxonMobil Baytown is the second-largest refinery in the U.S. and one of the largest in the world. More than half a million barrels of crude oil a day are processed. It also processes butyl, which is found in car tires and is not believed to be toxic to humans. The refinery also makes Polypropylene, which is used to make plastics.

In response to the fire and the chemical released, ExxonMobil released the following statement:

"We are committed to being a valued and respected member of the Baytown community, and we understand that public respect and confidence are earned through performance, open communications and community involvement.

We immediately contacted the City of Baytown 911 Center to report the fire at our facility. We also contacted the City of Baytown's Office of Emergency Management, which reposted the CAER message on its social media pages.

We posted a message to the Community Awareness and Emergency Response (CAER) online app to let the community know about the fire and that our industrial hygiene staff would be conducting air monitoring, and posted those updates on our Baytown area social media pages.

Within a few hours of the event, we also held a press conference with the City of Baytown's Office of Emergency Management and the Harris County Fire Marshall's Office. And we have issued a claims line number for community members to call and report any damage."