A drug-taking failed asylum-seeker dragged a woman into a Canterbury car park and sexually assaulted her.
Predatory Housny Boulaiz was only stopped when three men saw him leading the girl into the darkness and decided to intervene.
Sentencing him to three and a half years in custody, a judge at Canterbury Crown Court also recommended Charlie Vanstone, Edd Withers and Sam Eagleson receive a High Sheriff’s Award.
The 18-year-old Moroccan, whose asylum claim has been rejected by the Home Office, was convicted of kidnapping and sexual assault after a trial.
Judge Heather Norton told him: “You are well-practised and predatory and are willing to take risks to meet your offending needs.”
The attack took place on November 5 last year.
Mr Withers, 30, was working for his cake delivery firm when he spotted the girl, who had been on a night out, being led to a car park behind a business on the Sturry Road.
“I only just saw it out of the corner of my eye, but it just didn’t look right,” he said.
“We went over there and he was literally in the process of assaulting the young woman.
"He was lying on top of her and no one knows really what might have happened.
“Charlie started to film the guy and then chased after him when he ran away.
“The girl was very shaken up by it. We were just in the right place at the right time.
“It’s frightening, but I’ve been in Canterbury 10 years now and nothing like this has ever happened to anyone I know.”
Mr Vanstone, 23, was the first to arrive and asked Boulaiz what he was doing before chasing him as he fled.
He said: “We were pretty angry about what we’d seen. Before he ran off, Boulaiz was denying what he was up to, but it was clear that he was about to have sex with the victim.
“Canterbury is a pretty loving city, but obviously it can attract the wrong people.”
Mr Withers and Mr Eagleson, 23, took the girl to her home while Mr Vanstone helped police look for Boulaiz, who is of no fixed address.
They did not find him and police later issued a public appeal for him, placing him on their “most wanted” list.
John Barker, defending, said Boulaiz came to the UK on a lorry when he was 10.
He left his home in Morocco when he was eight after his mother threw hot oil over him, leaving him permanently scarred.
Sending Boulaiz to a young offender’s institute, Judge Heather Norton told him: “It is likely at the end of your sentence you will be deported – but that’s not a matter for me.”
"It's frightening, I've been in Canterbury 10 years and nothing like this has happened to anyone I know" - Edd Withers
Housny Boulaiz and two other failed asylum-seekers were also part of a “hugger mugger” gang who robbed a Taiwanese student of his mobile phone.
Ting Yo Lin had been walking along St Peter’s Street near the Black Griffin pub when Boulaiz approached him.
He said: “I was alone and he was saying to me that he wants to get to know me and be my friend.
“He was wearing a large blue hoodie with the hood up and claimed to be Turkish.”
Mr Lin said the man appeared to be drunk and kept hugging him, saying he wanted to be friends.
“After a few minutes of talking and hugging, two others turned up saying they also wanted to be my friend.”
During the exchange the student’s £600 mobile phone was stolen.
Boulaiz, Moroccan Yassine Hamadoni, 20, from Ashford, and Algerian Adil Nazar, 27, from Gillingham, were all convicted of robbery.
After the jury’s guilty verdicts , the prosecutor revealed the three had all claimed asylum but had been rejected by the Home Office.
Hamadoni, who was on bail at the time of the mugging, had previous convictions in October last year for burglary and 10 shoplifting offences going back to 2013.
He was also convicted in the same year of a sex offence in London.
Judge Heather Norton told Boulaiz: “You are a person who preys on vulnerable people in order to commit these offences and get funds to sustain your drug habit.”
Investigating officer detective sergeant Richard Lown said: "Boulaiz targeted this woman because she was alone and vulnerable and had planned to do her great harm.
"Thankfully the three men who approached the scene helped to stop him in his tracks."