A loosely organized group of "thugs" from central Canada and the U.S. that attaches itself to any cause and promotes anarchy formed part of the group of protesters who turned violent in downtown Vancouver's streets Saturday, police said.

"These protesters have within their ranks people we haven't seen before," Vancouver police Chief Jim Chu told reporters.

Police said the anarchists travel to any event that attracts media coverage and "promote anarchy wherever they go."

They also employ a tactic called "black bloc" where they dress in black and cover their heads and faces.

"That makes it difficult in terms of identifying them for specific criminal acts," Chu said. "And, as I said, their tactic is to hide among the ranks of legitimate protesters."

A CTV News crew followed a group of individuals as they ran away from the scene of the protest and changed out of black clothes and into regular street clothes behind a garbage Dumpster.

According to police, the protesters smashed department store windows, kicked and spray painted cars and knocked down newspaper boxes.

While some protesters beat drums and chanted slogans, such as "Homes not Games" and "No Olympics on stolen native land," others marched down the streets chanting "Revolution" and "Insurrection."

SFU security expert Andre Gerolymatos told ctvbc.ca Saturday that anarchists might latch on to whatever issues there are in the communities they are in, but their ultimate goal is to provoke police and make them look bad in front of TV cameras.

"They look at legitimate authority as the enemy and see themselves as the solution," he said.

Anarchism saw a resurgence in the 1990s, particularly in Europe and the U.S., he said.

In December 2008, anarchists -- upset over the fatal shooting by police of a teenager -- threw Molotov cocktails and rocks, smashed windows of shops and hotels in central Athens.

It was among some of the worst rioting seen in Greece in decades.

Gerolymatos said it would not surprise him if the anarchists escalated their violence in Vancouver in the days ahead.

"I suspect they may have retreated and will come back," he said.