Staff were ordered out of the building on Frobisher Way shortly after 11am when an ammonia alarm went off.
Two fire crews from Taunton and an environmental protection unit from South Molton attended the hazardous material incident.
A Devon and Somerset Fire and rescue Service spokesperson said: “Upon arrival of the crews staff had evacuated and confirmed an ammonia detector was activating and the leak was contained to within the building.
“Crews used breathing apparatus to investigate along with gas detection equipment.
“Crews monitored the internal conditions along with a chemical specialist and confirmed that ammonia levels were low enough for staff to return into the building.”