TORONTO -- There are growing calls for the federal government to declare a national day of mourning in honour of the 215 children whose remains were found on the site of a former residential school in Kamloops, B.C.

As of Monday morning, more than 28,000 people have signed a petition on Change.org calling for the federal government to do exactly that.

"Survivors of residential schools and their families carry the burden of this tragedy and it is due time that Canada as a whole also share this burden. These deaths impact every person in this land and so it’s important that we all come together to mourn," the petition says.

The Mississaugas of the Credit First Nations (MCFN) in Ontario issued an open letter on Saturday, seeking some action from Prime Minister Justin Trudeau’s Liberal government.

“We call on the Prime Minister to lower flags of this country and declare a national day of mourning for our children," said MCFN Chief R. Stacey Laforme in the letter. "For these Children and the many others!"

On Sunday, Trudeau tweeted that he’d requested flags at all federal buildings be flown at half-mast.

Mayors across Canada have also lowered flags at municipal facilities, as have provincial and territorial legislatures.

In Parliament, MPs on Friday unanimously agreed to fast-track the passage of Bill C-5, which would establish a National Day for Truth and Reconciliation as a new statutory holiday.

The bill was first introduced in September as part of the government's plans to implement the Truth and Reconciliation Commission's Call to Action #80. It follows a similar bill introduced by the NDP in 2017 that was heavily rewritten by the Liberals before dying in the Senate two years later.​

"It is an important action to take, and we must act immediately so that this day becomes part of our reality this year," said Canadian heritage minister and bill sponsor Steven Guilbeault in the House of Commons on Friday.

NDP leader Jagmeet Singh is also asking House speaker Anthony Rota for an emergency debate in parliament to discuss the discovery in Kamloops.

"Important questions deserve to be asked about this and other schools, and immediate concrete measures need to be taken as a way to seek justice and uphold the rule of law," Singh said in his letter to Rota on Monday.

REMEMBERING THE 215 CHILDREN

People across Canada reacted to the discovery over the weekend too, creating makeshift memorials outside provincial legislatures, residential school sites and in public squares.

Many feature scores of children's shoes, left to symbolize the hundreds of children found buried in Kamloops.

Public schools and teachers' unions across the country encouraged staff and students to wear orange shirts Monday. This echoes the ritual of Orange Shirt Day, marked annually on September 30 to honour the victims of the residential school system.​

The Kamloops school operated between 1890 and 1969, when the federal government took over its operation from the Catholic Church. It continued as a day school until its closure in 1978.

At one point, the school was the largest out of more than 130 schools in Canada's residential school system.

The Truth and Reconciliation Commission issued its final report on residential schools more than five years ago. The nearly 4,000-page account details the harsh mistreatment inflicted on Indigenous children at the institutions, where at least 3,200 children died amid abuse and neglect.

The remains of the 215 children in Kamloops were found with the help of ground-penetrating radar, the Tk'emlups te Secwepemc First Nation said on Thursday.

The Federation of Sovereign Indigenous Nations is calling for more forensic searches at other former residential school sites.

“We respectfully request all First Nations across our traditional lands to join us in this very important lobby effort," the FSIN said in a news release on Sunday.

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If you are a former residential school student in distress, or have been affected by the residential school system and need help, you can contact the 24-hour Indian Residential Schools Crisis Line: 1-866-925-4419

Additional mental-health support and resources for Indigenous people are available here.

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With files from The Canadian Press.