Madison firefighters were at Memorial Union shortly after 3:30 p.m. on Thursday to combat the fire which was extinguished by 4 p.m., said Madison fire Department spokeswoman Cynthia Schuster. According to Schuster, the fire was discovered underneath roof tiles of the Union. A portion of tiles had to be removed to put out the fire and some water damage occurred on the fourth floor of the building as a result. The cause has not been determined and the fire remains under investigation.