Council Bluffs fire officials have determined the cause of a fire that damaged an apartment complex earlier this week. Officials say improper disposal of smoking materials is believed to have sparked the fire at the Copper Creek Apartments at 2704 East Kanesville Boulevard Monday afternoon. Crews arriving at the scene found heavy flames extending up the exterior balconies and into the attic. Firefighters brought the blaze under control about an hour after arriving. All of the apartment's occupants escaped safely. One firefighter was treated for heat exhaustion.