Black-clad demonstrators burned police cars and smashed windows with baseball bats and hammers when rioting broke out at the G20 summit.
Some protesters hurled bottles at police after they prevented them approaching the perimeter of the economic summit site.
Heavily-protected riot police responded by firing tear gas
'This isn't our Toronto and my response is anger,' Toronto Mayor David Miller said. 'Every Torontonian should be outraged by this.
A police car burns after violent anti-G20 protesters, using Black Bloc tactics, smashed their way through downtown streets in Toronto
Violent protesters burned police cars, smashed shop fronts and confronting the 20,000 police who were charged with keeping order during the first day of the G20 Summit
A protester kicks a burnt-out car as a police vehicle burns in the background during an anti-G20 demonstration
'A relatively small group of people came clearly with the intent of damaging property and perpetrating violence.
'They're criminals that came to Toronto deliberately to break the law.'
The city's police chief Bill Blair admitted police had struggled to control the crowds, and had used tear gas on one occasion, after warning people to stay away from trouble spots.
'We have never seen that level of wanton criminality and vandalism and destruction on our streets,' he told an evening news conference.
'There are limits to free speech, and these limits really end when it infringes on the rights and the safety of others.'
At least 130 people were arrested, including some Blair believed were ringleaders of the rioting that started when several hundred anarchists broke away from a large, peaceful demonstration against the top-level meeting.
A protester plays his guitar as a police car burns during an anti-G20 demonstration
During an afternoon and night of rioting, police cars were set ablaze in at least two areas, including the city's Bay Street financial core, while protesters on hip Queen Street smashed storefronts and damaged media trucks.
By evening, some protesters had advanced to the metal fence sealing off the area where heads of state from the Group of 20 industrialised and developing countries were meeting. A downtown hotel was locked down, with riot police outside.
Banks, coffee shops and small stores were also targets and protesters looted at least one retailer, storming out with both clothing and the white arms and legs of fashion mannequins.
Toronto Mayor David Miller told a news conference. 'They're criminals that came to Toronto deliberately to break the law.'
The roving band of protesters in black balaclavas shattered shop windows for blocks, including at police headquarters, then shed some of their black clothes, revealing other garments, and continued to rampage through Toronto's downtown core.
Sealed with a kiss: A man and a woman kiss as riot police advance during a protest against the G-20 and the G-8 summits in Toronto
Protesters torched at least two police cruisers in different parts of the city.
Police in riot gear and riding bikes formed a blockade, keeping protesters from approaching the security fence a few blocks south of the march route.
They closed a stretch of Toronto's subway system along the protest route and the largest shopping mall downtown closed after the protest took a turn for the worse.
A stream of police cars headed to Toronto to reinforce security there after the smaller Group of Eight summit ended in Huntsville, Ontario.
The vandalism in Toronto's downtown area occurred just blocks from where President Barack Obama and other world leaders were meeting and staying.
Previous major world summits also have attracted massive, raucous and sometimes destructive protests by anti-globalisation forces.
The security costs are estimated at more than £600 million and include an estimated 19,000 law enforcement officers drawn from all regions of Canada.
Two activists kiss while protesting in front of a line of riot police during the G20 Summit in Toronto
Saturday's protest march, sponsored by unions and dubbed family-friendly, was the largest demonstration planned during the weekend summits.
Its organisers had hoped to draw a crowd of 10,000, but only about half that number turned out on what was a rainy day.
Toronto Police Sgt. Tim Burrows said before Saturday's protest that authorities were pleased by the demonstrators' orderly behavior.
Hundreds of protesters moved through Toronto's streets on Friday, but police in riot gear intercepted them, preventing them from getting near the summit security zone downtown.
Ontario's provincial government quietly passed a regulation earlier this month allowing police to arrest anyone who refuses to show identification or submit to searches if they come within five yards of a security fence.
Toronto's downtown core resembles a fortress, with a big steel and concrete fence protecting the summit site.
Previous global summit protests have turned violent. In 1999, 50,000 protesters shut down World Trade Organization sessions in Seattle as police fired tear gas and rubber bullets.
There were some 600 arrests and £2 million in property damage. One man died after clashes with police at a G-20 meeting held in London in April 2009.
At the September G-20 summit in Pittsburgh, police fired canisters of pepper spray and smoke and rubber bullets at marchers.