HOUSTON (AP) " A fire at a Texas chemical plant Tuesday that sent plumes of black smoke into the air killed one worker and injured at least two others, authorities said, in the second major blaze at a Houston-area chemical facility in about two weeks.

Harris County Sheriff Ed Gonzalez confirmed the fatality in a tweet and said the two injured had been taken by helicopter to a hospital.

Authorities shut down a roadway near Tuesday's fire at a KMCO chemical plant in Crosby, about 25 miles (40 kilometers) northeast of Houston, Gonzalez said.

All residents within a one-mile radius of the plant were ordered to stay indoors or shelter in place.

Harris said the fire was burning isobutylene, a flammable colorless gas used in the production of high octane gasoline. First Responders were trying to contain fire, Gonzalez said.

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.

John C. Foley, CEO of KMCO, said in a statement that the company had activated its emergency response team and set up a command center.

"We are working with local first responders to extinguish the fire," he said.

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.

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.