Police responded to a radio call of a subject looking into parked vehicles with a flashlight in the 300 block of North Rose Avenue around 3:55 a.m.
When officers arrived, they found the underage suspect tampering with the passenger side window of a parked vehicle.
Police detained the 17-year-old and found he was concealing a replica firearm in his front waistband. The suspect was also in possession of a pair of gloves and a utility tool.
During the later investigation, officers determined the suspect had forced entry into another vehicle and removed property.
He was taken to juvenile hall for auto burglary and possession of a replica firearm.