Authorities in Canada have uncovered the remains of 215 children, some as young as three years old, at the site of a former residential school for indigenous students.
Canadian Prime Minister Justin Trudeau on Friday described the discovery as heartbreaking.
The children were students at the Kamloops Indian Residential School in British Columbia, which closed in 1978, according to the Tk'emlúps te Secwépemc Nation.
Chief Rosanne Casimir said in a statement that their remains were found with the help of a ground-penetrating radar specialist.
In 2015, a six-year investigation into Canada's now-defunct residential school system found that it committed "cultural genocide," forcibly separating indigenous children from their families.
The report documented horrific physical abuse, rape, malnutrition and other atrocities suffered by many of the 150,000 children who attended the schools, which were typically run by Christian churches from the 1840s to the 1990s.
It found more than 4,100 children died while attending the schools.
That figure does not appear to include the previously undocumented discovery of the 215 children, buried under what was once Canada's largest residential school.
In 2008, the Canadian government formally apologized for the system.
In a tweet on Friday Trudeau called the news a "painful reminder of that dark and shameful chapter of our country's history."
The Tk'emlúps te Secwépemc Nation said it was reaching out to the home communities of the victims.
They expect to have preliminary findings by mid-June.