A police officer was punched and partygoers threw glass bottles at other officers at an out-of-control party in Warnbro overnight.
Police were called to a house in Teraglin Way in Warnbro just after midnight to reports that people were fighting on the street, a police spokeswoman said.
"Officers arrived to find around 50 people, mostly juveniles, in the street. Many were acting in a disorderly manner, with fights occurring and bottles being thrown," she said.
"Police declared it to be an out of control gathering and attempted to disperse the crowd.
During the incident, a male police officer was punched by an unknown man and officers were hit by glass bottles being thrown at them."
Police dogs and the mounted section, as well as regional operations group officers cleared the area.
Inquiries will continue.