VANCOUVER, British Columbia (AP) — Leaders of Indigenous groups in Canada say investigators have found hundreds of unmarked graves at the site of a former residential school for Indigenous children — a discovery that follows last month's report of 215 bodies found at another school.

The bodies were discovered at the Marieval Indian Residential School, which operated from 1899 to 1997 where the Cowessess First Nation is now located, about 85 miles (135 kilometers) east of Regina, the capital of Saskatchewan.

Chief Cadmus Delorme of the Cowessess said Thursday that a search with ground-penetrating radar resulted in 751 ''hits," indicating that at least 600 bodies were buried in the area.

Delmore told the Associated Press that at one time the graves were marked, but the markers were removed by the Roman Catholic Church, who operated the school.

Delmore said "The Pope needs to apologize for what happened," the AP reported.

Earlier this month, a report by the Truth and Reconciliation Commission said at least 3,200 children died due to abuse and neglect, and that between 1915 and 1963, 51 deaths at the Kamloops school were reported.