A Toronto city worker power-washes a spray-painted sidewalk along Bay Street in downtown Toronto on Sunday, the morning after vandalism broke out during the G20 summit. (Carolyn Kaster/Associated Press)

Dozens of store owners are cleaning up broken glass in downtown Toronto on Sunday after "thugs," as described by the mayor, caused widespread damage several blocks from the G20 summit venue.

David Miller denounced Saturday's vandalism by so-called Black Bloc protesters, who splintered off from the main demonstration. He suggested many of these people were not from Toronto.

"I will not dignify their activity by calling them protesters, because they are not," Miller said. "They are not welcome in this city."

A man gives a talk in front of the TD Bank at Bay and Queen streets in Toronto on Saturday afternoon. (Showwei Chu/CBC)A march that drew thousands of people — estimates ranged from 4,000 to 10,000 — carried on peacefully before up to 300 militant members in the crowd began to vandalize storefronts and vehicles in mid-afternoon, including setting fire to police cruisers.

At one point, the Eaton Centre had to be locked down, even though it's well outside the security perimeter.

"It was mayhem," said Mary Jane Webber of Dartmouth, N.S., who was on vacation and shopping at the Eaton Centre when the doors were locked.

"There was no certainty about anything. It was clearly security guards who had initially been told don't let anyone out, but you could see people outside trying to get in, and nobody seemed to know what the official information was from anybody.

'It was amazing to see how quickly the veneer of our civilization disppeared.'— Shane St. George, Toronto resident

"And then we started to hear things about blood, and then we started to hear about police cars on fire, and then we started to hear things about ambulances. So there was no direct information from anybody, and we were just really glad to get out out of the mall when we did."

Broken glass needed to be picked up in front of the Starbucks at John and Queen streets in Toronto. (Showwei Chu/CBC)CBC's Muhammad Lila, reporting across from the Eaton Centre on Sunday, said he counted about two dozen damaged stores within a two-kilometre stretch on Yonge Street. "It doesn't appear they looted anything."

Bird's-eye view of violence

There are retail stores on street level and condo units above, so hundreds of people watched events unfold from their balconies.

"It was amazing to see how quickly the veneer of our civilization disppeared," said Shane St. George, who lives in the area.

"We've lived downtown for 25 years and never seen anything like this. I think it's a nice neighbourhood and a nice city, and suddenly that was all gone. It's no different than what happened 400 years or 4,000 years ago."

Many stores along the downtown portion of Yonge Street have their windows fully boarded up and were expected to remain closed for the day.