A Beloit police school resource officer took the student into custody at Beloit Memorial High School around 12:45 p.m. Friday. Police say the teen was carrying a semi-automatic handgun.
Police and school officials were following up on a threats complaint. Beloit school district spokeswoman Melissa Badger says the threats were not school-related and were aimed at someone outside the district.
Police say the boy was taken into custody without incident. An investigation found the handgun was reported stolen earlier in the day from a residence in Beloit.
The boy is in detention pending court proceedings early next week.