Chopper 6 flew as over the scene shortly after noon in the 700 block of East 14th Street.
Action News learned that pepper spray somehow spread through three residence halls around 11:30 a.m.
More than 50 students in Hanna, Thayer and Grasselli Halls were evacuated. At least 5 were sickened by the fumes.
Firefighters worked to air out the buildings, then all students were allowed back in.
Investigators say the pepper spray was accidentally released in Hannah Hall.