An off-duty Atlanta police officer followed his instincts and interrupted a robbery in northwest Atlanta.

Lt. Terry Joyner noticed four juveniles acting suspicious on Bolton Road Wednesday, so he parked his car to keep an eye on them. His intuition was correct: As he sat there and watched, one of the juveniles walked into a gas station with a gun and robbed the clerk, police said.

Joyner immediately called for backup and helped arrest the 15-year-old suspect. Nearby, they found the replica gun used in the robbery, said Sgt. Curtis Davenport, an Atlanta police spokesman.

The name of the suspect was not released because he is a juvenile.