Portable electric heaters overloaded the wiring in a Camas rental home early Saturday, sparking a fire that damaged the residence, according to a bulletin from the Camas/Washougal Fire Department.The fire was reported at 1:33 a.m. at 305 N.W. 12th Ave. in Camas after someone awake in the house noticed the smell of smoke and that the lights weren’t working. Four people, ranging in age from 2 to 24, evacuated.The fire was found in a main floor bedroom wall extending to the second floor, and firefighters were able to significantly limit the fire damage, the bulletin said.A fire marshal discovered that because the house did not have a source of heat, the renters plugged in multiple electric heaters, which overloaded the old knob-and-tube wiring, causing it to fail and start the fire.Although people were using sleeping areas on all three floors, there was only one smoke detector installed on the second floor and none on the main floor or in the basement, the bulletin said. The home was not equipped with a fire sprinkler system or a carbon monoxide detector.The Red Cross was contacted for possible assistance to the family. The estimated damage was under $10,000.