A 16-year-old Portland resident was being held at Long Creek Youth Development Center after being arrested and charged with carrying a concealed handgun with an altered serial number.

A Portland officer pulled the teenager over on Interstate 295 just before 10:30 p.m. Thursday because of suspended license plates. The teen was driving past an 8 p.m. curfew, a condition set under his release on previous charges, with the suspended plates and no driver’s license, police said.

Following a search, the officer discovered the teenager had a Ruger 9 mm pistol in his pocket, with the serial number altered in what appeared to be an attempt to conceal it.

Police charged the teenager with criminal simulation and operating without a license. He was sent to Long Creek Youth Development Center, the state’s only prison for minors. Police did not release information on the boy’s identity or prior charges.