Children as young as nine have been arrested for a shocking catalogue of crimes - including drug trafficking, homicide, sexual offences and supplying Class A drugs.
Figures obtained by the Yorkshire Evening Post reveal police have made more than 11,490 arrests in West Yorkshire against young people, aged 17 and under, in less than three years.
Over 4,650 of those young suspects detained by police were living in Leeds.
Children have been arrested on suspicion of a number of offences including drink driving, fraud, forgery and possessing Class A drugs.
More than 1,560 arrests were made for allegations of criminal damage between January 2012 and July 2014.
A further 1,370 arrests were for domestic break-ins and there have been 730 arrests for robbery.
West Yorkshire Police said there has been a “consistent reduction” in the number of children detained by officers.
The force made 5,017 arrests in 2012 compared to 2,135 in seven months this year.
But campaigners said arresting a child can damage their future prospects.
Andrew Neilson from the Howard League for Penal Reform said: “Our research has found that West Yorkshire Police made almost 20,000 child arrests in 2008 and the number has been coming down ever since, thanks in part to a major Howard League campaign to keep children out of the criminal justice system.
“Arresting a child can damage their prospects in many ways, such as preventing them from gaining a university place or finding work as an adult.
“Children who have been in contact with the police frequently are more likely to reoffend than those who haven’t.
“Serious offences involving children are thankfully very rare.
“A sharp fall in the number of boys and girls entering the justice system is good news for everyone striving to reduce crime.”
Assistant chief constable Geoff Dodd said the decision to charge a young person is not made lightly.
He said: “West Yorkshire Police are properly focussing their attention on supporting victims, meeting the needs of communities and reducing offending.
“Crime, whilst at the lowest level for a generation, continues to be committed by a broad range of offenders and for a variety of reasons.
“Last year, West Yorkshire Police Officers arrested 23,000 suspects in Leeds; around seven per cent of these arrests were of suspects under 17 years of age.
“However, arrest is not automatic; officers have to consider whether it is appropriate and necessary.
“The care that officers take is particularly relevant when dealing with younger suspects.
“Wherever it is appropriate, officers will often deal with young people outside of a formal custody system.
“There are occasions however, when due to the seriousness of the offence, pursuing a criminal prosecution against a person under 17 is the right thing to do.”