Ohio University staff and faculty evacuated Haning Hall late Thursday afternoon when the fire alarm was set off by a freon leak.
The building will likely be closed until tomorrow morning, according to a statement from Joseph Lalley, senior vice president for information technologies.
Freon is a aerosol propellent.
Lalley said an air conditioner compressor failed in Haning Hall's basement sometime before 5 p.m. Thursday, causing the leak.
He added that Athens Fire Department arrived on the scene and cleared the building.
Joshua Lim contributed to this report.