An explosion of undetermined origin destroyed an unoccupied building at the ICI Americas plant (Atlas) at Reynolds last night.

Michael Wentkoff, site director at the plant, said the building, a wood-frame, one-story structure, about 25-by-40 feet in size, was allowed to burn itself out over a period of four to five hours.

All persons on the plant site were evacuated as a precaution.

The affected building was the Aero Spade Mix Pack area. Material made there is a propellant fuel and there was an estimated 5,000 pounds of the material in the building at the time.

Schuylkill County Emergency Management coordinator Art Kaplan, who was on scene during the blaze, said no toxic chemicals were released in the incident.