VIDEO: The Iowa City Fire Department is investigating a fire at an apartment early Saturday morning. Firefighters responded at 7:35 a.m. to a report of an oven fire with smoke at 427 North Dubuque Street. The arriving crew found a working fire in an apartment on the 4th floor. According to the fire department, 16 firefighters extinguished the fire in approximately 20 minutes. The building sprinkler system contained the fire to the room of origin. Damage to the apartment and contents is estimated at $20,000. No injuries were reported. The cause of the fire remains under investigation.