SAN DIEGO - Firefighters don't know what started a structure and grass fire on South Julian Street, according to Capt. Mando Tunchez with the Alice Fire Department.

Alice firefighters responded to a fire in San Diego Wednesday afternoon after firefighters from the town could not be reached. San Diego Fire Department is made up of volunteers who work during the day, most out of town.

Alice firefighters called Duval County Emergency Services Department #2 firefighters for mutual aid. When firefighters arrived they immediately began to extinguish the fire.

The fire consumed the old Duval County Precinct 1 building that had been vacant for several decades.

"We don't know how it started," Tunchez said. "There were no obvious reasons how the fire may have been started."

According to neighbors, they didn't see anyone in the area before the fire. They smelled smoke, saw the property on fire and called 9-1-1.

The fire burned approximately an acre of grass around the structure.

A Duval County employee used a front end loader to remove debris from the area.