A fire early Wednesday morning caused heavy damage to an apartment house at 211 North 12th Street.

Firemen were called to the location about 2-AM and when they arrived heavy smoke was coming from the structure.

Fire officials say the building has four apartment units and the fire started in a unit on the first floor to the rear of the building.

One of the occupants of  the apartment dwelling was treated and released at Trinity Regional Medical Center. The other occupants have been displaced because power to the building has been turned off.

The blaze is now under investigation, according to the Fort Dodge Fire Department.