A 16-year-old DeKalb County girl will spend a month in juvenile detention for bringing a gun to Columbia High School, authorities said.

The girl pleaded guilty on Monday in DeKalb County Juvenile Court to charges of carrying a gun at school and possession of a pistol or gun by a minor, DeKalb County District Attorney’s office spokesman Erik Burton told the Atlanta Journal-Constitution.

The teen was sentenced to 30 days in the DeKalb County Juvenile Detention Center, between nine and 12 months probation and 35 hours of community service, court officials said.

Her name is being withheld because she is a minor.

She was arrested on Sept. 17 after a Columbia High student tipped off the principal that she was carrying the loaded 9 mm handgun found in her purse, authorities said.

A second DeKalb school gun incident last week involved a fight outside Stone Mountain High School as students were dismissed from school.

As the brawl ensued, several non-students jumped into the fray, and the small-caliber pistol fell from one of the individual’s pockets, witnesses told authorities.

Two were arrested in that incident, school officials said.

The Columbia High student will go before a juvenile court judge in January for a status hearing, authorities said.