A 19-year-old man has been arrested by detectives investigating the serious sexual assault of an 11-year-old boy.
The boy was threatened with a handgun before the assault on Blue Gowt Lane in Spalding, Lincolnshire on the afternoon of 23 December.
The man is being questioned at Spalding police station.
Police said the victim was walking along the road with a nine-year-old boy when he was approached by a man on a motorcycle. The other child ran off.
The boy was treated at Boston Pilgrim Hospital and released.
Police said he was "badly traumatised" by the attack.