Station 27,36,15,46 were alerted to Freeport High School.for an Automatic Fire Alarm. T-36 went enroute very shortly after dispatch. T-36 was first to arrive on scene and establish command. 36 Crew was met at the front door by the evening Maintenance dept. Maint. thought it to be a panel malfunction as there was a call there recently before, but upon further investigation it was found to be a pull station that was accidently tripped. All units went back in service without incident. Units on scene T-36, E-27. 15, 46 were held in station.