The Gardiner Expressway has reopened in both directions after a protest by Tamil-Canadians took an unprecedented turn Sunday night, as thousands of protesters spilled onto the busy roadway and blocked it for hours.

The crowd gathered across from the U.S. consulate and then moved south to take over the highway. Just after midnight, people began leaving the area and police reopened the downtown artery.

This latest move was not pre-planned and appears to have been sparked by the community's anger over reports of 378 civilians killed in Sri Lanka Saturday night. In fact, protesters say the numbers are grossly underestimated and the total is closer to 3,000.

They are demanding to meet with an official from Prime Minister Stephen Harper's office.

Dozens of police, some in full riot gear, were called in to contain the crowd and although there were no reports of anyone hurt yet, the group appeared to be volatile.

Police Chief Bill Blair called the demonstration "unlawful" and "unsafe."

"I'm very concerned about the safety of children, I think it's an extremely dangerous situation to put children on the front line of a protest in that way, I think it puts them at tremendous risk," he noted late Sunday.

Mayor David Miller, meanwhile, was calling for calm and for Tamil demonstrators to peacefully move to a safer location.

"Toronto's Tamil community is understandably concerned about what is happening to friends and family in Sri Lanka," he said in a statement. "They have an absolute right to make those concerns known and to protest. Endangering public safety by occupying the Gardiner or other public highways is not the right way to make that statement."

Traffic was backed up for kilometres and throughout the downtown core. And police closed the Don Valley Parkway southbound for several hours

Several hundred Tamil-Canadians also blocked the intersection of College Street and University Avenue not far from the stretch in front of the U.S. Consulate they  occupied for several days more than a week ago.

Sunday's protest began earlier in the day at Queen's Park, where Gunabalasuntharam Veerakathipillai is also on his eighth day of a hunger strike.

He and his supporters say they are frustrated by the lack of response from the international community and want government officials in Canada and the U.S. to step in and put an end to the violence thousands of kilometres away.

The conflict is centered in the northern part of the country, where Tamil Tigers are fighting for a separate state. A Sri Lankan health official says in addition to those who died in an artillery barrage Saturday, more than 1,100 people have been injured. But the military has denied the accusations.

Tamil-Canadians and peace activists also staged a demonstration on Saturday with a march that ended at the U.S. Consulate.

Below are photos taken by CityNews viewers of the crowds approaching the Gardiner Expressway.

Photo credits: CityNews viewers Sarah Peterson (top two) and Gary Kane (bottom)

Another Tamil Rally Descends On U.S. Consulate

Scuffles Break Out As Tamil Protest Enters Its Third Day

University Avenue Finally Reopens As Police Move Tamil Protesters Onto Sidewalk