Firefighters responded at about 7:05 a.m. to a report of a structure fire at 801 W. Grand Ave., according to Battalion Chief Robert Lipp.
Firefighters quickly contained the blaze that appeared to have started near an electrical box on the outside of a commercial building, Lipp said.
The firefighters then went into the building, discovered the grow operation, and notified police, according to Lipp.
Arriving officers found the plants, which have a street value of between $350,000 and $750,000, Thomason said.
He said arson was not suspected, and that the fire likely started because the circuit was overloaded with the lights and ventilation system inside the structure.
No arrests have been made in connection with the grow operation, Thomason said.