CRESSON, Texas - Hazardous materials crews have resumed the search for a worker who is missing and presumed dead following an explosion at a Texas chemical plant that injured two co-workers.

Texas Department of Public Safety Staff Sgt. Earl Gillum says recovery crews are using heavy equipment Friday to clear burned debris at the Tri-Chem Industries plant in Cresson, 50 miles southwest of Dallas.

Investigators believe a worker dragging his foot along the floor while chemicals were being mixed sparked Thursday's explosion. That worker is hospitalized with critical burns. Another worker was treated for less severe injuries.

The search resumed Friday for the third worker who Gillum has said is presumed dead.

Gillum says experts determined there are no air quality issues but the site remains dangerous because of the hazardous industrial chemicals.

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