An Airsoft BB-style pistol was found. No injuries were reported.
The lockdown was lifted, according to message posted just after 3 p.m.
Two juveniles were detained in connection with the incident, police said.
Niles West High School lock down has been lifted, Scene secured, No injuries more information to follow.— Skokie Police (@skokiepolice) October 2, 2017
A parent had contacted police, telling them that their child had told them a fellow classmate had brought a gun to school.
Anyone with information is asked to contact the Skokie Police Department at 847-982-5900 or the 24-hour Skokie Crime Tip Hotline at 847/933-TIPS (8477). Text-A-Tip is available 24-hours a day by texting "Skokie" and your tip to 847411.