Three more people have been arrested after two related incidents in Mandurah and Coodanup on Tuesday.
At around 6.40pm, a fight broke out at the Mandurah Aquatic and Recreation Centre.
Three hours later, police were called to another disturbance in Coodanup involving a group related to the earlier incident.
A 17-year-old boy from Mandurah has been charged with aggravated assault occasioning bodily harm and taking part in a riot.
He will appear before the Juvenile Justice Team.
A 12-year-old girl from Mandurah has been charged with participating in a riot and was issued a Juvenile Caution.
A 15-year-old girl from Mandurah has been charged with participating in a riot and threatening behaviour and was also issued a Juvenile Caution.
Police inquiries are continuing.
Female passenger dies after horror Kwinana Freeway crash
Havana Brown and Thelma Plum to headline 2026 Crab Fest
Hazmat warning issued after rubbish truck catches fire in Kwinana Beach
WA Police ramp up patrols near schools as students return for Term 1
Fire engulfs car then spreads to bushland in Oakford
Community bands together to provide essential school supplies to local children
Detectives continue to hunt man who dragged woman by hair into bushes in Halls Head
Woman airlifted to hospital following South Yunderup crash
Shire of Murray celebrates outstanding citizens