Vancouver Mayor Gregor Robertson called the violence "disgraceful." He said: "We have a small number of hooligans on the streets of Vancouver causing problems. It's absolutely disgraceful and
shameful and by no means represents the city of Vancouver.
"We have had an extraordinary run in the playoff, great celebration. What's happened tonight is despicable."
The violence started when fans set fire to a stuffed bear decorated to symbolize the Boston Bruins.
Police started using flash-bangs - grenades, which are made to distract and disorient, rather than injure - to break up the mobs.