The incident occurred Wednesday morning at the Beasley Elementary Magnet Academic Center. It prompted an emergency medical services plan response which called for multiple ambulances to arrive on the scene, said Chicago Fire Department spokesman Larry Langford.
He added the children were taken in good condition to area hospitals.
Parents were notified and the student responsible was removed from the school, Chicago Public School spokeswoman Marielle Sainvilus said.
The Chicago Tribune reported officials initially referred to the liquid as pepper spray but later said they could not confirm it.