BAYTOWN, Texas (KXAN) – Four people are being treated for injuries after a fire and possible explosion Thursday in Baytown, east of Houston. The Harris County Sheriff’s Office called it a “major industrial accident” at an oil refinery.

ExxonMobil Baytown confirms the fire started around 1 a.m. at its facility. Officials there tweeted people nearby may see emergency vehicles and smoke in the area. According to the Houston Business Journal, the facility is part of the largest petrochemical manufacturing complex in the U.S. This is the facility that produces gasoline.

At a press conference early Thursday morning, Refinery Manager Rohan Davis said everyone is accounted for and the four people injured are currently “stable,” but would not say how severe the injuries are. He would also not confirm that the fire sparked an explosion.

Davis says ExxonMobil is monitoring air quality as firefighters continue to battle the fire.

According to the Harris County Sheriff, there are no reports right now to evacuate or shelter-in-place. Sheriff Ed Gonzalez also wrote on Twitter four people had to be taken to the hospital by helicopter, another went by ambulance.

Many people on social media reported feeling and hearing the blast.