As campaigners and politicians discuss sexual exploitation in conflict at a global summit in London, experts say rape in UK gangs often mirrors the violence in war zones - and does not get the attention it deserves.
"I don't know many girls who haven't been raped," says Toni, a 16-year-old girl who got drawn into gang life in London through her relationship with a gang member.
Though there is no research showing exactly how widespread the problem is, rape is being used by street gangs in neighbourhoods across Britain.
Female victims are caught up in a brutal dynamic that observers say reflects what happens during conflict, but has become so common that it is normalised.
"The conflict mentality within these gangs means that young girls are being horrifically sexually exploited and humiliated by their male peers," says Helen Beckett, who researches sexual violence in youth at the University of Bedfordshire.
"You get passed around the gang," says Toni. "There are so many of them that you can't stop them."
She says she was raped by a 19-year-old gang leader when she had just turned 15.
"I begged him to not touch me, but he started screaming at me, breaking bottles, and threatened do all sorts of things to my family," she recalls.
"I tried to go home, but the rest of the boys wouldn't let me leave. I gave in after a while.
"I'll never ever get over it."
'Used as tools'
London has more than 200 gangs made up of about 3,500 members, according to the latest estimate by the Metropolitan Police.
Some of those involved are girls, but they have a different role from the male gang members, says Lola Mustapha, youth ambassador for the Safer London Foundation.
"They're not really fighting, they are being sexually exploited and used as tools," she says.
In many cases, she adds, "a gang might kidnap and rape the girlfriend or sister of a rival to punish him".
Girls also may be used as a "honey trap", or "set up chick", to lure a gang member to a location where the rival gang will beat him up.
But that girl then becomes a target.
"If the rival gang catch her they beat her and rape her," explains Rachel, a 15-year-old who was also a victim of sexual violence in a London gang.
"Some have been [urinated] on, their clothes ripped off, and then [the gang members] will post the pictures of it on social media and make her life a living hell."
"They tell her - I've done it to you and I'll do it again or worse, and so she's trapped with that rape happening to her again and again."
Because of the photos on social media, there may be abuse from people the girl does not even know.
Rachel also mentions the risk of a girl's own gang turning her into something akin to a sex slave.
She says a friend of hers was raped by her boyfriend, then forced to have sex with the whole gang.
"They took videos of it and then they blackmailed her, saying they'd post it all over the internet if she doesn't do whatever they want. It's basically prostitution."
Rachel says many of the girls she knows feel suicidal, and she ended up in hospital herself several times following suicide attempts, before getting help from the charity NIA Ending Violence.
Carlene Firmin, the head of MsUnderstood Partnership, a non-governmental organisation that aims to improve youth gender inequality, says there are several parallels with sexual crimes committed during wars.
"The fact that the rape is often 'multiple perpetrator' and done in public, not private, is similar to what happens in conflict zones," she says.
"When you have ongoing gang conflict in neighbourhoods over a long period of time, then the impact is similar to that of other conflict zones in terms of post-traumatic stress disorder and a permanent sense of being unsafe."
But Ms Firmin also says that lessons learned about sexual violence in conflict should be passed on to those working with gangs.
"There remains a gulf between how rape in gang conflict and rape in war are conceptualised and addressed," she says.
"Both are often motivated by territorial conflict between groups. Women and girls who are raped in this context rarely seek help and support, or have their victimisation recognised by professionals."
Rachel and Toni are now both in care and have managed to get out of gang life. Because they are still at risk their names have been changed.
They agreed to speak out in order to highlight what is happening to so many young girls in the UK. Social workers say their stories are so common they could have been told by any number of girls in London.
"More women need to come forward", says Rachel. "Girls don't know that once they're in secondary school they're going to face sexual exploitation and I think they should be taught."
Helen Beckett points out that the violence "isn't happening in a vacuum".
"Women are seen generally as sexual objects in wider society. The gang is a hyper-masculine environment and it just ups the ante."
Leana Hosea's full report is on the BBC World Service's Newshour programme from 12:00 GMT on Friday. You can also listen back here.