Detectives are questioning a man about the double rape of a 15-year-old girl in west Belfast yesterday morning.
He was arrested as part of a major PSNI hunt for two men involved in the sex attack.
After the assault the rapist called his young victim's mother on a stolen mobile phone to gloat over what he had just done.
Armed with a screwdriver, he subjected the girl to two sex assaults early yesterday morning.
A second man used a metal bar to batter three boys she was with and stop them rescuing her. It is understood the man arrested is not the suspected rapist.
The girl, who is from the north of England but was holidaying in Belfast, was left severely traumatised by the double rape.
She was confronted by the pair as she walked along Blacks Road with friends just before 3am.
Cash and mobile phones were stolen before the girl was dragged into a BP petrol station forecourt and raped.
The boys, two 15-year-olds and one aged 14, were ordered to strip to the waist and beaten repeatedly.
All four were then taken up a driveway at the nearby Colin Valley Golf Centre where the girl was raped again.
Detectives have been told the man with the iron bar claimed to be called Terry from the Divis area of west Belfast. The rapist is believed to be five feet, eight inches tall, with a cut under his left eye and chipped and decaying teeth. His partner's left ear was pierced and he wore at least one sovereign-type ring.
Detectives have urged the rapist and his accomplice, both thought to be in their late teens, to give themselves up. Their families were also challenged to bring them to a police station if they suspected their involvement.
PSNI Chief Superintendent Ken Henning described the attack as horrendous and disgraceful. "It has caused untold distress to the victims and their families," he said.
"The individuals who carried out the attack took her mobile phone, rang her mother and told her what they had done," Mr Henning added.