A shelter-in-place order is issued after a fire at an ExxonMobil plant in Baytown, Texas

Residents have been asked to shelter in place near parts of a massive ExxonMobil plant in Texas where emergency crews were responding to a fire on Wednesday, officials said.

Three people sustained minor injuries, said Natasha Barrett, the spokeswoman for city of Baytown. They were transported to a hospital.

The fire occurred at the company’s Baytown Olefins Plant, according to ExxonMobil spokeswoman Sarah Nordin. The company website describes the complex as one of the largest refining and petrochemical complexes in the world. It’s located about 25 miles east of Houston.

The blaze is in a unit that contains polypropylene material and Exxon asked that a shelter-in-place order be issued west of the plant and south of the Texas Spur 330 freeway “out of an abundance of caution,” the city of Baytown said via Twitter.

“Our fire teams are working to extinguish the fire,” Nordin said in a statement. “We are conducting personnel accounting. Our first priority remains the safety of people, including our employees, contractors and the surrounding community.”

She said the company is conducting air quality monitoring at the site and fence line, and cooperating with regulatory agencies.

Harris County Emergency Management tweeted: “Shelter-in-place means to stay indoors, keep doors and windows closed, turn off the air conditioning. Exxon is conducting air monitoring and will advise when the danger has passed.”