The county fire marshal’s office said that a warehouse at the plant was on fire and officials were “trying to determine what products are involved.”
One employee told KPRC television that the plant was in the process of being evacuated because workers were told that there was a leak of some sort.
The employee said the plant exploded as about 20 workers were leaving. He said employees had to crawl under a gate because the gate was locked.
Messages left with KMCO were not immediately returned.
The Texas Commission on Environmental Quality said that it has dispatched emergency response personnel to conduct an initial assessment of the fire.
The fire comes about two weeks after a March 17 blaze at a petrochemical storage facility in Deer Park, located about 20 miles (32 kilometers) south of Crosby. That earlier fire burned for days and triggered air quality warnings.
According to its web site, KMCO is a chemical company that offers coolant and brake fluid products and chemicals for the oilfield industry.
The Crosby, Sheldon and Channelview school districts have asked students and staff to shelter in place at all their campuses.