Earlier this month Cowessess started using ground-penetrating radar to locate unmarked graves. It was not immediately clear if all the remains are connected to the residential school.
Cowessess Chief Cadmus Delorme spoke at a virtual news conference Thursday morning.
"This is not a mass grave site. These are unmarked graves," Delorme said.
An Indigenous group said the remains of 751 people, mainly children, had been found in unmarked graves on the site of a former boarding school in Saskatchewan.