Police officers in Hamilton were pelted with bottles on Saturday night as they moved in to break up what they say was an out-of-control party.
The police say they had to deploy dogs and form a skirmish line to disperse a large crowd of mostly drunk 14-to-16-year-olds at a party in the suburb of Dinsdale.
They say the partygoers were pushed towards a reserve, where they dispersed in various directions. Many calls came from people reporting suspicious activity as the partygoers fled through private properties to escape.
Two boys, aged 14 and 15, identified as alleged ringleaders, were arrested and face charges of riotous behaviour and assault with a weapon.
The Hamilton police say they're taking a zero-tolerance approach to alcohol-related violence.