A 16-year-old boy was busted with a loaded handgun as he tried to get into a Queens high school during a basketball practice Sunday, police sources said.

The .38-caliber handgun was found on the teen around 10:15 a.m. when he went through a metal detector at John Adams High School on Rockaway Boulevard in South Ozone Park, the sources said.

A basketball practice was going on in the school at the time, sources said.

The teen was charged with criminal possession of a weapon on school grounds and criminal possession of a loaded firearm.

His name wasn’t released because he’s a juvenile.