(CNN) — Law enforcement officials were on the scene of a “major industrial accident” at the ExxonMobil plant in Baytown, Texas, early Thursday, officials said.

Initial reports are that some type of explosion occurred inside the plant, Harris County Sheriff Ed Gonzalez said in a tweet. Four people may be injured, he said, three of whom were taken by Lifeflight and one by ambulance.

Residents in the area, which is about 25 miles from Houston, reported a loud explosion.

ExxonMobil said a fire occurred at the facility just after 1 a.m. local time.

The company said in a tweet it was coordinating with local officials and working to resolve the issue as soon as possible, but no other details were provided.

The Baytown refinery began operations in 1920 and the chemical plant started in 1940, according to the ExxonMobil corporate site.

Located along the Houston Ship Channel, the Baytown operations — including four manufacturing sites and a global technology center — are located on about 3,400 acres, according to the company, and employ about 7,000 people.

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