Engine Co. 4 was called to Memorial Union for a fire alarm activation. While on scene, firefighters noticed smoke in the first floor kitchen that was getting thicker. Engine 4 prompted a full structure fire response, summoning multiple additional fire crews to the scene.

Engine Co. 4 located a custodial room where an automatic fire sprinkler had activated. There, firefighters found piles of oily kitchen rags smoldering. Memorial Union staff confirmed there was a bag of wet rags with oil mixed in them stored inside the room. The rags are believed to have spontaneously combusted, resulting in fire that triggered the automatic fire suppression system. Ladder Co. 1 remained on scene with Engine Co. 4 to ventilate the smoke and help overhaul the rags.

The Memorial Union was retrofitted with automatic fire sprinklers in recent years during remodeling projects that took place between 2012 and 2017. Without the presence of automatic sprinklers, this incident may have grown much larger before being noticed, and significant damage could have occurred to this historic building.

Following this incident on August 21, damage was contained to the room of origin and an adjacent office. The Memorial Union was re-opened to the public by 12:30 p.m.