City : EPA tests have not found significant levels of chemicals in the air . The plant 's owner says an electrical spark may have caused the blaze . On Monday , Dave Bary -- a Dallas-based spokesman for the EPA -- said the most prevalent chemical that the plant 's owner had documented , and produced on site , was anhydrous ammonia . The plant produced chemicals used in fracking , its CEO tells CNN affiliate WFAA . - May 13 :
City : EPA tests have not found significant levels of chemicals in the air . The plant 's owner says an electrical spark may have caused the blaze . The plant produced chemicals used in fracking , its CEO tells CNN affiliate WFAA . - May 13 :