A post-hockey game riot that saw violent mobs looting stores and burning cars in downtown Vancouver last week, has spawned a frenzy in cyberspace to catch those responsible for damaging property and wrecking the laid-back Canadian city's image.
The smoke and tear gas had barely cleared when websites sprang up showing pictures and amateur videos taken amid the violence. The sites called on the general public to shame the rioters and identify them to police.
The Internet outrage has been so strong that the Vancouver Police Department warned on Monday "there is a growing danger that the tools of social media will be used to mete out vigilante justice."
The riot was an abrupt comedown for the city, which is known for is easy-going West Coast attitude and had been praised for its handling of the 2010 Winter Olympics, including large peaceful street parties.
Police initially blamed the riot on "anarchists" -- including some who had tried unsuccessfully to stop the Olympics -- but conceded on Monday it also involved many young people with no previous criminal records.
At least 117 have been arrested on various charges and police say arrests will continue as investigators sort through the thousands of images sent in by the public.
While Internet-posted images have provided police with a treasure trove of evidence, they could also alert some rioters that their identifies are known, said Robert Gordon, a criminologist at Simon Fraser University.
"It's a double-edged sword," Gordon said, adding there has probably been "a run on hair dye" for rioters who want to change their appearance.
The pictures also run the risk of wrongly implicating people who were in the area, but neither participating in nor encouraging the violence, warned Robert Holmes president of the British Columbia Civil Liberties Association.
The family of one rioter who tried to burn a police car, but later turned himself in, told local media they were forced from their home over threats generated by the teenager's image on the Internet.
Despite warning against vigilantes, Vancouver Police Chief Jim Chu also played on the public outrage by also warning that rioters who do not surrender will be arrested "in a public manner suitable to the public crimes you have committed."
"If you come in voluntarily you can do so discreetly, and at a time that is convenient for you," said Chu, whose department has been accused of not being prepared despite a similar hockey riot in the city in 1994.