Firefighters responded to the facility off of Villa Avenue and Bullard where they found heavy smoke pluming from the unit.
Crews fought the fire from the outside of the building. No one was inside when the blaze broke out.
"We went defensive immediately, (we) put crews on the exterior on all four sides, broke out a couple of the windows and doors, and hit it with some hose lines to knock it down," said Clovis Fire Battalion Chief Anthony Gomes.
Clovis Fire officials said the building stored various items. A majority of the property inside belonged to the Clovis Police Department as well as the Public Utilities Department.
The cause of the fire is under investigation.