Smith County Assistant Fire Marshall Oren Hale said a faulty air conditioning system caused the fire in the server room of FedEx Home Delivery at 3815 NNE Loop 323.
The fire started shortly before 5 p.m., Hale said. An employee who was closing up the building for the day smelled smoke and noticed the door to the server room was hot.
Hale said the employee called emergency personnel immediately. The fire was contained to the one room with smoke and fire damage in the ceiling and attic area as well, Hale said.
The Jackson Heights Volunteer Fire Department responded to the scene.