A Chicago firefighter has been charged with gun violations after his 14-year-old daughter posted a photo of herself online posing with his assault-style rifle.

The photo carried a message: "Don't worry, I won't shoot up Lane," referring to Chicago's Lane Tech College Prep High School. It's unclear when she posted the picture.

The Chicago Tribune says the 60-year-old firefighter was cited for failing to secure a weapon from a minor and possessing an assault rifle in the city. His daughter hasn't been charged.

Security at Lane Tech called police after the photo appeared on Snapchat. It isn't clear if the girl is a student at the school.

Chicago Public Schools spokeswoman Emily Bolton says there was no credible threat. She says families were assured in a letter Wednesday.