Authorities were called out to an office complex at 216 Mall Boulevard around 11:30 a.m. Friday.
According to the Upper Merion Fire Marshal, a machine in the building leaked fluorine gas.
The machine is designed to shut down when this happened and also clean the fluorine out of the air.
According to the fire marshal, the machine worked properly and when they arrived on scene there were no traces of fluorine in the air.
The building was evacuated as a precaution for about two hours while MontCo Hazmat crews responded to the scene. Everyone was allowed back inside the building and there were no injuries.