Investigators are on the scene at a building at the main Ohio University campus.
It happened around 3:25 p.m. Tuesday.
The "unknown situation" occurred at Clippinger Hall, which is the science laboratory building, according to the Ohio University Police Department.
Police tell 13News students were told to leave their belongings in the building and evacuate.
The area surrounding Clippinger Hall, University Terrace, was closed for approximately one-hour to traffic, but has reopened.
However, the building remains closed while crews investigate the situation.