A 14-year-old boy brandished a pellet gun at a Rockland County middle school yesterday, then waved it at passing cars outside until one of the drivers — a retired NYPD cop — wrestled it away, police said.

It was the second gun scare at the school in less than a year. Orangetown Police Chief Kevin Nulty said the boy, who was in an office with a teacher and another student at South Orangetown Middle School in Blauvelt when he pulled the realistic-looking gun, was taken into custody.