MILWAUKEE, WI (CBS 58) -- A home on Milwaukee’s north side was severely damaged by a fire late Saturday night.    Around 11:20 PM, Milwaukee firefighters were called a fire in a 1-and-a-half story structure at N 12th Street and North Avenue.   When they arrived, the home was fully engulfed in flames.   Firefighters spend around 90 minutes putting out the fire.   About 85 percent of the building was damaged by the fire.   No one was present at the time and authorities believe the house may have been vacant.   The cause of the fire is under investigation.