There were signs of mounting tension between police and protesters Thursday afternoon as uniformed officers continued to question people walking through Toronto's so-called security zone ahead of the G20 summit.

With the city on high alert as world leaders start to arrive, police have had some serious concerns.

On Thursday afternoon, police arrested the driver of a suspicious vehicle and confiscated weapons including a chainsaw, sledge hammer and crossbow. They also laid charges against a second person in an explosives investigation that was announced Wednesday.

Also on Thursday, about 1,000 protesters marched in support of native rights, gathering at Queen's Park, located just blocks north of the G20 security zone. Police were also hearing reports that another group of demonstrators would attempt breach the security fence surrounding the G20 summit venue. That protest never materialized.

But as the street activity ramps up in advance of the summit, some protesters expressed surprise at the extra scrutiny of their movements.

A group of young men who had been at a community mobilization meeting said police went too far, pulling them aside for questioning while ignoring the two white men and Asian girl they were walking with.

"It was a complete case of racial profiling," said Navyug Gill, one of the men questioned.

The three men, one of whom was sporting a T-shirt that says "G20 child care," were approached by five police officers as they walked west on Front Street towards University Avenue.

They were stopped on their way to a meeting about protest action, Gill said. Police immediately questioned one man about his T-shirt.

"They asked our names, demanded ID and asked if we were afraid to give them our ID," he told CTV.ca. "We were afraid. We didn't know what they wanted to do with us so we complied."

He said police took notes and called headquarters to verify their identities.

"We told them we're here to protest against the G20 and we're walking on our streets in our city."

Const. Tim Garland, spokesperson for the Integrated Security Unit, said a regulation had passed giving police authority to question anybody coming into the restricted zone from June 14 until June 28, the day after the summits are scheduled to end.

G20 security points start at Lake Shore Boulevard to the south, north to King Street, east to Yonge Street and reach west to Spadina Avenue.

"If you're in that zone you're going to be challenged," he told CTV.ca.

"To accuse the police of racial profiling is unfair and certainly not the way we're operating," he continued. "If you're going to be wearing a T-shirt with an anarchist slogan, it's going to catch the attention of police. It's common sense."

But Gill says while he and his friends disapprove of the high-profile government summits, the T-shirt did not have an anarchist message.

He said the man wearing the shirt was a volunteer who was tasked with approaching families at rallies to make sure they had enough sunscreen and juice for their young children.

Gill said these kinds of encounters with authorities "create mistrust between police and the public."