A fire in Green Lake overnight severely damaged a duplex. Fire crews were called to the structure on Meadowlark Lane just before 3:30 this morning. Personnel broke through the roof to get at the blaze. There were people in one of the duplexes at the time of the fire. They all got out safely. One firefighter was taken to Ripon Hospital with exhaustion, and a police officer was treated at the scene for minor smoke inhalation. The cause of the fire remains under investigation.