VANCOUVER -- First Nations communities across B.C. are in mourning after the remains of 215 children were found on the site of a former residential school in Kamloops.

The discovery illustrates the damage the school system continues to cause, even decades after being disbanded.

The remains were found last weekend using a ground-penetrating radar.

The Tk’emlúps te Secwépemc band is now working with the Royal British Columbia Museum to see if any records of the deaths can be found.

Chief Rosanne Casimir called it an “unthinkable loss.”

“We had a knowing in our community that we were able to verify. To our knowledge, these missing children are undocumented deaths,” she said in an interview with CTV News Friday.

The band will be working with the coroner and reaching out to surrounding communities that had children who attended the school.

The Kamloops Indian Residential School operated between 1890 and 1969 and was once the largest in Canada’s residential school system.

The Union of B.C. Indian Chiefs is calling on all Canadians to give pause.

“This is the reality of the genocide that was, and is, inflicted upon us as Indigenous peoples by the colonial state. Today we honour the lives of those children, and hold prayers that they, and their families, may finally be at peace,” said Grand Chief Stewart Phillip.

B.C. Premier John Horgan also offered his condolences Friday saying he was horrified and heartbroken.

“I honour Tk’emlúps te Secwépemc as they grapple with this burden from a dark chapter of Canadian history and uphold their commitment to complete this investigation over the coming weeks – bringing to light the full truth of this loss,” he said in a statement.

More than five years ago, the Truth and Reconciliation Commission report found at least 3,200 Indigenous children died from abuse and neglect at institutions across the country.

A SHOW OF STRENGTH

A survivor of the school system spoke to CTV News about what he remembers, following news of the discovery.

“It was life-changing and there were a lot horrific things that happened to myself, and I know a lot of individuals that were in that school system," said Chief Harvey McLeod of the Upper Nicola Band.

Among those are members of his family and his community.

The chief, too, is a survivor of the school, and says the news was difficult to hear.

"One of the huge revelations that happened to me yesterday was me realizing my strength that I didn't know that I had as a child, the strength to survive and walk away from that school and be here today."

He says he carries the pain of what he experienced with him to this day.

“I always thought I was a weak man, but now I know how much I had to be able to come home and be where I’m at today,” he said.

McLeod says he still remembers the faces of the kids who went missing.

“We didn’t really talk about it too much because I was one of the people that said, ‘I’m going to run away. I’m going to get away from this place.’ But after seeing some of my friends come back getting caught and saying how they were treated, we decided that we’ll just tough it out.”

He says now is the time for the community to come together and find a way to move forward.

“Ensure that the remains that are found are taken care of in a good way and we be there and support our people that are grieving,” he said.

A National Indian Residential School Crisis Line has been set up to provide support for former residential school students and those affected.

Emotional and crisis referral services can be accessed by calling the 24-hour national crisis line at 1 866 925-4419.

Heritage Park in Kamloops is closed to the public while work gets underway.

Tk’emlúps te Secwépemc expect to complete preliminary findings by mid-June.