Two people were taken to hospitalized in "critical/serious" condition, the Chicago Fire Department said. Spokeswoman Eve Rodriguez did not have information on the victims' ages or gender.
Police had initially said the students were in good condition.
The shots were fired at the Chicago Vocational Career Academy at about 2:30 p.m., police spokeswoman Monique Bond said. A student with a handgun shot an unarmed student in the leg, and a bullet apparently ricocheted and struck the shooter in the leg.
She said a gun was recovered at the scene.
School officials could not immediately provide any information.