Two Shreveport families have been displaced by overnight house fires.Shortly after midnight, a single mother and her three children escaped a fire in their single-story wood-frame house in the 2600 block of Huntington Avenue. Fire investigators have traced the cause of that fire to grease left unattended on the kitchen stove. Investigators are still trying to determine the cause of another fire -- reported about 3:45 -- in the 200 block of College Street. But Chief Fred Sanders say candles are a possibility -- since the two adults living there had continued to do so despite a fire in the attic three days earlier and had been using candles throughout the house for lighting. That fire took over an hour to bring under control.