ST. LOUIS PARK, (AP) - Firefighters have evacuated an office tower in a Twin Cities suburb where they responded to a report of an explosion and fire in the basement.

Fire officials say a transformer exploded and knocked out power to the building in St. Louis Park Thursday.  Hundreds of workers and customers in the building were evacuated.

Air conditioned tents were set up for firefighters because of the high heat and humidity. Firefighters from Golden Valley, Excelsior, Minnetonka and other communities were called to assist.