CHAPEL HILL, N.C. — A burn victim of the Kinston plant explosion died Monday, raising the death toll from the Jan. 29 tragedy to six.

Allen Grant died at the North Carolina Jaycee Burn Center at UNC Hospitals, a spokeswoman said.

The condition of another patient was upgraded. Kenneth W. Simien was listed in fair condition. He had been in serious condition.

James Edwards remained in critical condition, while James Hardison was in serious condition and Javier T. Xochicale was in good condition.

A mix of dust and air fueled the explosion at the West Pharmaceuticals medical fittings factory, sparking a fire that burned for days, federal investigators said.

Inspectors said they have not determined what kind of industrial dust fueled the explosion or what sparked it.