Anti-G20 protesters set up camp at a Toronto park Friday evening after at least 3,000 people noisily marched through the downtown streets, snarling traffic along the way.

Following the first sizable protest, a few hundred people set up a couple dozen tents at Allan Gardens, not far from the summit meeting centre, where they said they will camp for the weekend. Most of the tents were red, with messages scrawled on the side including "Housing is a right" and "End homelessness now."Protesters set up dozens of tents at Toronto's Allan Gardens to camp out during the G20 summit weekend. (Amber Hildebrandt/CBC)

The protest was mostly peaceful, although there were a few minor confrontations and skirmishes with police. The Integrated Security Unit said five G20-related arrests were made Friday, but did not specify whether they were linked to the protest.

The demonstration began around 2 p.m. ET at Allan Gardens, where there were speeches were made and slogans chanted.

Shortly afterward, protesters took to the streets, marching west along nearby Carlton Street, across Yonge Street and then south on University Avenue.

A Bike Unit member orders the crowd to move back as a demonstrator is arrested by College Park Shops at Yonge and College Streets in Toronto. (Showwei Chu/CBC)

All along the route, police blocked traffic to allow the protest to pass by. Streetcars were rerouted throughout the downtown core. Security staff in some buildings temporarily prevented employees from leaving.

Just before 6 p.m. ET, more than 100 police stopped the protest crowd at Elm St. and University Avenue, several blocks north of the U.S. consulate and less than two kilometres from the site of the G20 summit.

"Let us march!" they shouted at the police. The group then decided to head west on Elm Street, averting a major confrontation with officers.

"Restraint on both sides," CBC reporter Pras Rajagopalan said from the scene.

The protest then moved north and then east again as police appeared determined to prevent the crowd from heading south toward the security zone surrounding the summit site.

Just after 7 p.m. ET, the protesters began arriving back in Allan Gardens, having come full circle from where their protest march began more than four hours earlier.

Many police donned riot gear during the protest.

"There were some tense moments," said CBC reporter Steven D'Souza. More than a dozen police on horseback were also on scene.

At one point, police formed a line to protect Toronto police headquarters, which is at Bay and College streets.

Protesters were making themselves heard, loudly chanting, "Fight the war on the poor! Make the rich pay!" among other slogans.

It's not clear if their ultimate destination was the downtown core's restricted zone, where a security fence encircles an area that includes the Metro Toronto Convention Centre — the site of the G20 gathering, which officially begins Saturday.

Some of the protesters told CBC News they intend to establish a tent city at a downtown park but did not specify which one.

The groups represent more than two dozen causes, including environmental, economic and labour issues.

Organizer Gaetan Heroux said the group intends to make noise to ensure G20 delegates are aware of their presence.

"The idea is to have at this time a group of world leaders wining and dining in five-star hotels, sleeping very well at nighttime while five minutes away from them, there's a large group of people who don't have enough housing and don't have enough to eat," said Heroux.

"So the idea is to bring the tent city … to remind our politicians and Mr. Harper that what he wants to present to the world is a lie."

With files from The Canadian Press