Sandridge School District 172 said a shelter-in-place was enacted at Sandridge School in Lynwood due to a domestic situation nearby.
The Cook County Sheriff's Office said police responded at about 11:40 a.m. to a report of shots fired in the 3000 block of Glenwood Dyer Road, where they found a 73-year-old male barricaded inside a home.
The man was later taken into custody without incident, and no injuries were reported.
Chopper 7 was over Glenwood Dyer Road as police investigated.
The superintendent said the lockdown was lifted before 4 p.m., and students were dismissed.
Further information was not immediately available.