PHILADELPHIA — A student tried to enter a Philadelphia high school Monday with a stolen .40-caliber handgun loaded with a dozen rounds, police said.

Capt. Sekou Kinebrew said it's unclear why the 15-year-old boy had the gun, which was found when the bag was scanned just after 7:30 a.m. at Samuel Fels High School in northeast Philadelphia.

"Right now it doesn't look like he was up there to settle a grudge or anything like that," Kinebrew said.

Kinebrew said the gun had been reported stolen from a car near the home of the student, who had no disciplinary problems or known issues with classmates. Kinebrew said the boy may have had the gun in the bag to conceal it from his parents.

The school was placed on lockdown. There were no injuries. The student faces weapons charges.

The Philadelphia Police Department regularly responds to reports of guns in schools but that it is "relatively rare" for a student to have an actual firearm, Kinebrew said. A state report tallied four incidents of handgun possession and 38 incidents of BB or pellet gun possession in Philadelphia schools last year.