Police swooped on a Hemel Hempstead traveller site this morning.
Around 20 officers were drafted in at 7.30am to make arrests at the Three Cherry Trees Lane site.
Seven people were taken into custody and items, including mobile phones, were seized.
Representatives from the court service were also there to collect unpaid fines and RSPCA officers went in to investigate concerns about animal welfare. It is understood that a number of dogs were taken away.
Dacorum Chief Insp Glen Channer said: “The activity was at a small number of properties on the site, based on intelligence about suspected criminal activity.
“While we were there our safer neighbourhood teams provided reassurance and information to residents and I would like to thank members of the community for their patience and support whilst we conducted enquiries.”
A 16-year-old boy, four men and two women were arrested on suspicion of offences that related to theft, making off without payment, non-payment of fines and perverting the course of justice.