The Madison Fire Department is investigating the cause of a small fire that occurred at the former Oscar Mayer headquarters Tuesday night. MFD spokesperson Cynthia Schuster said officials received a call at 9:10 p,m. for a report of a fire alarm that went off on the 900 block of Oscar Avenue. An ambulance and other units were also sent after an initial crew arrived and smelled smoke. An incident report said a security guard who was in the building found the fire on the 6th floor and used three fire extinguishers in an attempt to knock down the fire. Firefighters were able to extinguish the remainder of the fire using water can extinguishers. Officials said the security guard suffered minor injuries but did not need to be taken to a hospital. Several fans were used to ventilate the property of smoke, and the department’s Fire Investigation Team remains at the scene.