Girls involved in gang crime are being overlooked and failed by the authorities, the children's commissioner for England has said.
Half of children involved with gangs are girls and they "desperately need help to get out", Anne Longfield said.
They are often used to carry knives or drugs because they are less likely to be stopped by police, she told the BBC.
The Local Government Association said "limited funding" meant councils had to prioritise those at immediate risk.
'Under the radar'
Ms Longfield told the Victoria Derbyshire programme she was writing to the government and local authorities calling for a review into support for female gang members, who were "not getting the help they need".
"Teachers, social workers, GPs and youth workers need to be doing more to help get these girls out of gangs," she said.
"So many are trapped with nowhere to go."
Two-thirds of children in England assessed by councils as being involved in gangs are boys (66%) and one third girls (34%), figures analysed by the children's commissioner's office suggest.
Estimates from the Office for National Statistics suggest a higher figure - that as many as half may be girls.
But the Metropolitan Police Service's gangs matrix database lists 3,000 male gang members known to the authorities in London and just 18 female gang members.
And London's deputy mayor for policing, Sophie Linden, said a lot of girls were going "under the radar".
Nequela Whittaker, who used to be in a gang but is now a youth worker, said girls as young as 11 were now telling her they carried weapons for "boyfriends, other counterparts and gang members".
"As young as these girls are, they are not scared to carry a weapon and if something went wrong to use it," she told the Victoria Derbyshire programme.
"They are the ones who are getting away with it, mostly because they are not looked upon as a person of interest, as opposed to a young male."
Until recently, "Samira", 18, was a member of a south London gang who had groomed her into carrying weapons from the age of 12.
"It would mostly be kitchen knives, for gang members and for my own protection," she said.
Asked if she was aware of the harm this could lead to, she replied: "All you think about is yourself. You don't really care about what happens to the other person.
"All you want to do is protect yourself and you're willing to do anything to do that."
She said she had also seen other girls being sexually exploited by senior gang members.
"I saw people getting stabbed, getting shot, people getting beaten up and getting robbed," she said.
She is now pregnant, which she said had allowed her to escape gang culture.
Ms Linden, said it was heartbreaking to hear young girls talk about being groomed and abused.
"We are doing our best to engage with those we know about and make sure we are actively reaching out to communities, to ensure we are working with young women and girls who are being exploited.
"We haven't forgotten them."
The Local Government Association, which represents 370 councils across England, said: "Councils are being forced to divert the limited funding they have left away from preventative work, including young offenders teams and youth work, into services to protect children who are at immediate risk of harm."