The Iowa City Fire Department responded to a report of a house fire at 120 Potomac Drive at 12:51 p.m. Sunday. Crews reported an exterior fire that extended into the attic of a single-story single-family residence. Firefighters entered the house and had the fire under control within 23 minutes. Damage to the home is estimated to be $50,000. No injuries were reported. The cause of the fire is under investigation by the Iowa City Fire Marshal. The off-duty Iowa City Fire Department was called back to staff stations. Outside agency support was provided by the Iowa City Police Department, Johnson County Ambulance Service, Johnson County Joint Communication Center and MidAmerican Energy.