The Youngstown Fire Department responded to a chemical spill at 3:30 p.m. Tuesday in a lab on the fifth floor of Ward Beecher Hall.
The building was evacuated as a precaution.
One student suffered a chemical burn to his foot, and was treated at St. Elizabeth Health Center before being released Tuesday night, said Ron Cole, YSU spokesman.
Fire Chief Terrence Jordan said the evacuation occurred after a gallon of hydrochloric acid fell off a cart and spilled in the hallway outside of a classroom.
Another chemical fell from the cart but did not escape its container, the chief said.
Text messages and emails were sent to alert the campus to the closure.
All other buildings remained open.
Cole said Ward Beecher would reopen for classes at 6 a.m. today.