CALGARY, Alberta – The remains of 761 people, mostly indigenous children, were discovered on the grounds of a former school in Saskatchewan province, a Canadian indigenous group announced Thursday, rocking a nation that has been experiencing widespread and systematic abuse for generations by indigenous people.

The biggest discovery to date came weeks after the remains of 215 children were found in unmarked graves on the grounds of another former boarding school in British Columbia.

Both schools were part of a system that took indigenous children in the country, some by force, from their families over a period of around 113 years and placed them in boarding schools, where they were not allowed to speak their language.

A national truth and reconciliation commission established in 2008 to investigate, expose and document the history and consequences of boarding schools called the practice “cultural genocide”. Many children never returned home and their families were given vague or no explanations about their fate. Canada had approximately 150 boarding schools and an estimated 150,000 Indigenous children attended the schools between their opening in 1883 and their closure in 1996.

It is unclear how the children died in the church schools that were ravaged by disease outbreaks a century ago, and where children were exposed to sexual, physical and emotional violence and violence. Some former students of the schools have reported that the bodies of infants of girls who were impregnated by priests and monks were cremated.

The commission estimates that around 4,100 children are missing in schools across the country. But an indigenous former judge who headed the commission, Murray Sinclair, said in an email this month that he now believes the number is “well over 10,000”.

The discovery in Saskatchewan was made by the Cowesss First Nation at the Marieval Indian Residential School, about 87 miles from the provincial capital, Regina.

“There was always talk, speculation, and stories, but seeing that number – it’s a pretty significant number,” said Bobby Cameron, head of the Federation of Sovereign Indigenous Nations, the provincial association of indigenous groups. “It’s going to be difficult and painful and heartbreaking.”

He added, “This is what the Catholic Church in Canada and the then government of Canada forced upon our children.”

For Canada’s 1.7 million Indigenous citizens, who make up approximately 4.9 percent of the population, the discovery is a haunting reminder of centuries of discrimination and abuse that resulted in intergenerational trauma for boarding school survivors and their families.

It’s also a strong endorsement of their testimonies. While recent evidence has increased awareness of the subject, Indigenous peoples’ oral traditions had indicated for decades that thousands of children had disappeared from schools but were often met with skepticism. “There’s no denying it: all of our survivors’ stories are true,” said Chief Cameron.

The latest evidence is likely to deepen the country’s debate over its history of indigenous peoples exploitation and bring attention back to the horrors of schools, a flaw in the history of Canada, a country that has often, fair or not, been perceived as a bastion of progressivism and multiculturalism.

In September 2017, Prime Minister Justin Trudeau acknowledged the past “humiliation, neglect and mistreatment” of the country’s indigenous people and vowed to improve the lives of the country’s indigenous people in a speech to the United Nations General Assembly. The recent discoveries will put pressure on him to accelerate these efforts, which many indigenous people complain have been neglected.

When Mr. Trudeau took office in 2015, he made the 94 recommendations of the National Truth and Reconciliation Commission a top priority. But progress has been slow, in part because some of them are beyond the control of the federal government. The Indian Act, a nineteenth-century set of laws governing the lives of indigenous peoples, remains in place despite Trudeau’s promise to transform it into a new system under their control. Chief Cameron and several other Indigenous leaders hope that discovering the children’s remains will speed the process.

The remains of the 215 children were discovered using ground penetrating radar at the Kamloops Indian Residential School in British Columbia. Similar to an MRI scan of the body, the technology creates images of anomalies in the ground.

An official with the Federation of Sovereign Indigenous Nations said the latest analysis, based on the same technology, began about three weeks ago, not long after the Tk’emlúps te Secwépemc First Nation announced preliminary results on the Kamloops School.

The search at Kamloops School continues, and First Nation leaders said they expected the number to continue to spike.

When the commission tried to investigate the issue of missing indigenous children, the then Conservative government rejected its request for funds to fund searches. Since Kamloops was discovered in late May, several Canadian governments have offered to pay for the searches.

On Tuesday, the federal government announced that it would allocate just under $ 4.9 million Canadian dollars (about $ 3.9 million) to indigenous communities in Saskatchewan to search for graves. The provincial government had previously pledged Canadian dollars ($ 1.6 million).

In a statement, Saskatchewan Prime Minister Scott Moe predicted the remains of more children would be found elsewhere. “Unfortunately, other First Nations in Saskatchewan will experience the same shock and despair as the search for graves continues,” he wrote.

Like Kamloops, Marieval School, which opened in 1899, has been run by the Roman Catholic Church for the Canadian government for most of its history. A marked cemetery still exists on the site of the school, which was closed in 1997 and then demolished. The commission, based on testimonials from former students and archive materials, listed the Marieval School as a likely location for unmarked graves.

The commission asked for a papal apology for the role of the church, which ran about 70 percent of the schools. (The rest were led by Protestant denominations.) But despite a personal appeal from Mr. Trudeau to the Vatican, Pope Francis has still not taken this step. In contrast, the leadership of the United Church of Canada, the largest Protestant denomination in the country, apologized in 1986 for its role in running the schools.

Former Saskatchewan residential school students have been particularly active in litigation against the government that led to financial settlements and the establishment of a commission that over six years heard more than 6,700 witnesses testify.

Since the Kamloops announcement, Chief Cameron said he has toured the province where agriculture and mining are major industries and looked at former school sites.

“You can see with the naked eye the indentation in the floor where these corpses can be found,” he said of some places. “These children are sitting there waiting to be found.”

Vjosa Isai contributed to the research.