Dozens of youths gatecrashed a wedding in Bicton, causing fights with guests and throwing bricks and injuring guests at the reception last night.
Police say officers were called around 9.10pm after up to 50 youths arrived at Point Walter Cafe on Point Walter Road.
The gatecrashers had started asking wedding guests for cigarettes and became involved in stoushes with a number of guests.
"The incident began with a small number of youths asking one of the wedding guests for a cigarette earlier in the night," a police spokeswoman said.
"They then returned and again demanded a cigarette from the guest but were denied.
"An altercation occurred between the guest and the group.
"Other guests from the wedding came outside and assisted the man but were outnumbered when more youths arrived."
Police estimate at one stage up to 60 people were involved.
The youths then tried to force their way into the premises and started throwing bricks at the venue. Some struck a number of guests who received injuries.
The offending group had left the area prior to police arrival.
Around seven guests received injuries. Four men aged between 27 and 32 years and three women aged between 29 and 32 were hurt.
A number were conveyed to Fremantle Hospital for treatment to injuries either received during an assault or being struck by objects.
Police will review CCTV of the incident.
The group are described as being mostly dark skinned males, around 16-22 years old.
Anyone who can assist is asked to call Crime Stoppers on 1800 333 000.