Watertown Fire Rescue was called for a fire at Terex Fiberglass on Piper Ave at approximately 8:50pm on April 22nd. Fire was reported to be in the office area. Upon arrival there were no visible flames or smoke coming from the building. Employees stated that everyone was evacuated and uninjured. Firefighters made entry into the office area and was able to quickly knockdown the fire. Fire damage was limited to the office and break areas due to activation of the sprinkler system in those rooms. Full extinguishment of the fire was impeded due to the fire being in the floor joists between the office area and the upstairs breakroom. Cause of the fire is under investigation.  WFR was on scene for 2 hours.