A teen was arrested with a gun at his Brooklyn high school Friday — telling officials he needed it for “protection,” police and sources said.

The 17-year-old, whose name was not released because of his age, was searched by a school administrator at Medgar Evers College Preparatory High School in Crown Heights around 10 a.m. when officials believe he smelled like marijuana, police and sources said.

Officials found a revolver with a teal handle in his backpack, police and sources said.

The student told the administrator he “has it for protection,” sources said.

The youth is facing unspecified gun charges as a juvenile.

“Our outstanding school staff and School Safety Agents immediately recovered this item, ensuring that all students and staff are safe,” said Department of Education spokesperson Jenna Lyle.

“The safety and wellbeing of everyone in our schools is our absolute top priority, and dangerous weapons of any kind are not tolerated in our schools. All protocols were followed and we are working closely with NYPD regarding follow-up actions.”