The fire was blazing in a unit that contains polypropylene, a thermoplastic. Exxon asked for the Shelter in Place order to be issued west of it's plant and south of highway 330 "out of an abundance of caution."
Shelter in place means to stay indoors, keep doors and windows closed, and turn off the air conditioning, according to Fox 26 Houston.
No cause for the fire has been announced yet. ExxonMobil is working to extinguish the fire.
Exxon stressed in a statement that their "first priority remains the safety of people, including [their] employees, contractors and the surrounding community."