VIDEO: One person was killed and several others injured in a late Wednesday explosion and fire at a corn milling plant in Columbia County. Two of the 16 employees that were on shift at the Didion Milling plant on Highway 146 in Cambria were still missing as of about 5 a.m. Thursday, Sheriff Dennis Richards said during a press conference at the Cambria Village Hall on Edgewater Street. More than 35 police, fire and medical service agencies responded to the explosion and subsequent fire that caused a portion of the building to collapse.