Police were called to a Belper street after reports that a teenager had a gun.
Concerned members of the public called officers at about 7.15pm last night to report that there was a group of teenagers in Hunter Road and that one of them was carrying a gun.
Officers travelled to the scene, supported by the helicopter, and found the group.
One 18-year-old was arrested on suspicion of possessing cannabis, questioned and released on bail.
A BB gun was recovered nearby.
Anyone with information should call police on 101, quoting crime reference number 31022-15.