A fire caused by a “major industrial accident” at an industrial facility in the US state of Texas injured four people, the Harris County Sheriff's Office said on Thursday morning. The blaze at the ExxonMobil facility in Baytown that houses a chemical plant, an olefins plant and a 560,500 barrels-per-day oil refinery, began about 1am, the company said on Twitter. "Our fire teams are working to extinguish the fire. We are conducting personnel accounting," Exxon said. "At this time, emergency vehicles and flames may be noticeable to the community. We are co-ordinating with local officials, and working to resolve the issue as soon as possible," the message said. Emergency services including an air ambulance in the Houston area responded to the fire and ExxonMobil said it was working with authorities to tackle the blaze. 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. But, he said that there were no reported fatalities. Initial reports indicated there had been some type of explosion at the plant, he said. There were no reports to evacuate or shelter-in-place at the moment, the sheriff added. 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 tweeted about an explosion that shook buildings in the vicinity. There was a major fire at the site in 2019 in which 37 people were injured.