Saint Xavier said the incident happened in a biology class and that there were no injuries.
In a CFD tweet at about 5:30 p.m., officials said there was a "minor spill under investigation" and there is "1 possible injury."
A half gallon of hydrochloric acid was accidentally spilled, fire officials said.
Chopper 7HD spotted emergency vehicles outside the Warde Academic Center at the school, located in the 3700-block of 103rd Street on Chicago's Far South Side.
Haz-mat St. Xavier Univ. for chemical spill in science lab. Minor spill under investigation 1 possible injury. No transport as of yet.
— Chicago Fire Media (@CFDMedia) September 19, 2016
Haz-mat St. Xavier Univ. for chemical spill in science lab. Minor spill under investigation 1 possible injury. No transport as of yet.
— Chicago Fire Media (@CFDMedia) September 19, 2016