An 11-year-old caught with a knife was one of the youngest arrests made by Northamptonshire Police this year.
The child, who would have either been in primary school or had just started secondary school when arrested, was also arrested for criminal damage to property.
The youngster was released under investigation over the criminal damage and refused charge for the possession of the knife.
A Freedom of Information Act request by this newspaper has also revealed that another 11-year-old was arrested for arson in 2017.
They were also refused charge.
The two youngest arrests made by police in the county were both on 10-year-olds, arrested for theft from a shop.
An 11-year-old was also arrested for common assault and criminal damage to property.
Both that 11-year-old and the two 10-year-olds were released under investigation.
This newspaper also asked Northamptonshire Police for details about the oldest people they had arrested this year.
The force withheld details about the two oldest individuals arrested as they may be identified and could jeopardise investigations.
The oldest arrest they were willing to disclose was an 84-year-old drink-driver, who was charged and bailed to attend court.
An 83-year-old was arrested on a warrant and not given bail, while an 82-year-old was also arrested on a warrant and refused charge.
A similar Freedom of Information request last year revealed a 93-year-old arrested on suspicion of manslaughter was the oldest arrest in 2016.
The youngest was an 11-year-old burglar.