Police say they seized a "huge amount" of alcohol from underage drinkers at Chipping Sodbury Mop fair last weekend.
Police were concerend about the number of under-age drinkers
Many young people took cans and bottles of lager and cider as well as spirits to the fair despite police warnings.
Sergeant Andy McIlrath, said: "I am disappointed that officers policing the event seized a considerable quantity of alcohol, especially on Friday.
"There is no doubt in my mind that alcohol consumed by some of the youths led to a number of disturbances."
Three people were arrested over public order offences during the two-day fair in High Street, Broad Street and Wickwar Road.
A 15-year-old girl was reprimanded under the juvenile system, an 18-year-old teenager received an £80 fixed penalty notice for disorder and a 16-year-old boy was arrested on suspicion of assault.
Sgt McIlrath added: "Many of the youths claimed that they had obtained the alcohol from home, but even more of a concern was that some had stated their parents had supplied them with it."