A spokesperson for the Didion Milling plant in Cambria says a fourth person has died of injuries suffered in last week’s explosion.  Forty-six-year-old Angel Reyes was a pack operator at the plant.  He died at U-W Hospital in Madison.  The bodies of three other workers who died in the blast have been recovered from the rubble of the destroyed plant.  An ethanol plant located nearby was not damaged in the explosion and fire and some employees have started to return to work.  Company officials have said they plan to rebuild.