At 325 am Saturday a person called the Houston Fire Department to report a building fire in the 2500 block of Summer, just west of downtown. Fire units arrived to find heavy smoke from the two story structure. As firefighters made entry they found the fire to be contained in a 20 by 20 cubicle and quickly extinguished it. Smoke filled most of the block long two story structure and had to be cleared. Houston Fire Department Arson Investigators are on the scene attempting to determine a cause. Very little damage was done to the structure. Besides Betz Galleries, photographers, graphic artists and other artists occupy the building.