(NewsNation Now) — Four people are hospitalized after a fire erupted on Friday at Exxon’s Baytown, Texas refining and petrochemical complex, one of the largest refining and petrochemical facilities in the United States.

There were no fatalities and those injured were in stable condition, while other personnel were accounted for, Exxon said. The company said in a statement that the fire had been put out by roughly 10 a.m. ET, several hours after the blaze erupted.

An Exxon official told a news conference that the fire had affected a unit that produces gasoline. People familiar with plant operations told Reuters that the fire occurred in a hydrotreater unit at the refinery that had been shut on Wednesday due to a bypass line leak.

The injured were contractors who had been repairing the leak. Harris County Sheriff Ed Gonzalez said on Twitter that three people were evacuated by Lifeflight rescue helicopter and a fourth person was taken by ambulance.

Gonzalez said initial reports had indicated that there had been some type of explosion at the plant. Social media users said on Twitter that a blast shook buildings in the area.

The Baytown Police Department said the plant unit affected in the incident processed material with gasoline components.

Sources familiar with the Baytown complex operations said the fire was in the Baytown Olefins Plant but said no more details were immediately available.

Social media users said on Twitter that a blast shook buildings in the area.

The Baytown plant houses a chemical plant, an olefins plant, and the country’s fourth-biggest oil refinery, with the capacity to process 560,500 barrels per day of crude.