TOONE, Tenn. - A West Tennessee sheriff says an employee who was severely injured in a manufacturing plant explosion has died.

Hardeman County Sheriff John Doolen told WMC-TV on Monday night that Michael Chism, who was burned over 90 percent of his body in Saturday's blast, had died.

A response team of chemists, engineers and bomb technicians assembled by the Bureau of Alcohol Tobacco and Firearms began its investigation of the blast at Kilgore Flares plant in Toone on Monday.

Kilgore makes air and naval decoy flares for the military.

The ATF says they expect to determine the cause of the blast quickly.