(This story may be triggering for some readers.)

A third First Nation in B.C. has revealed the existence of many buried bodies near a former Indian residential school operated by the Missionaries Oblates of Mary Immaculate, which is a religious congregation of the Catholic Church.

In a newsletter this week, the Penelakut Tribe stated that it had located more than 160 "undocumented and unmarked" graves near the former Kuper Island Industrial School.

Kuper Island is a Gulf Island that now bears the name Penelakut Island.

The website of UBC's Indian Residential School and Dialogue Centre states that the school opened in 1890 under Catholic administration.

In 1969, the federal government took over operations of the school, which closed in 1975. It's since been torn down.

"Students set fire to the school in 1896 when holidays were cancelled," the IRSHDC states. "A survey carried out in that year showed that of 264 former students 107 had died.”

The Penelakut Tribe has not disclosed how it located the unmarked and undocumented graves.

A former student of the school, respected Vancouver Indigenous activist Kat Norris, described the school as a "torture chamber" in a 2007 interview with the Straight. She said at the time that she was sexually abused when she attended the school for three years in the 1960s.

In the video below, filmed in 2017 by UBC's Learning School, Norris disclosed that the perpetrator was a priest.

Norris is from Nanoose Bay, which was one of the home communities of the students. Others came from Beecher Bay, Burrard, Chehalis, Chemainus / Chemainus Bay, Chilliwack, Clemclem / Clemclemluts, Cole Bay, Comeaken / Comiaken, Comox, Cowichan, Equimalt, Galiano, Khenipsen / Ghenipsen, Halelt / Halalt, Katzie, Koksilah, Kuleets, Kwaw Kwaw A Plit, Ladysmith (Stz'uminus), Langley, Lyackson, Malahat, Musqueam, Nanaimo (Snuneymuxw), Patricia Bay, Pauquachin, Penelakut, Qualicum, Quamichan, Saanich, Siccamen, Skawahlook / Skawollock, Skwah, Somenos, Songhees, Sooke, Squamish, Tsartlip, Tsawout, Tseycum, Valdez, and Westholme, according to the IRSHDC.

The news about Kuper Island came nearly seven weeks after the leadership of the Tk’emlúps te Secwépemc disclosed that it had located the remains of 215 children on the grounds of the now-closed Kamloops Indian Residential School. This was done with the help of ground-penetrating radar.

According to Kukpi7 (Chief) Rosanne Casimir, these were undocumented deaths, with some of the children as young as three years old. These were described as preliminary findings.

On Thursday (July 15), the Tk’emlúps te Secwépemc leadership will present the media with a presentation on the ground-penetrating report findings. In addition, there will be statements from Kamloops Indian Residential School survivors and an intergenerational survivor.

The event will be livestreamed through Vimeo and the Tk’emlúps te Secwépemc Facebook page and website.

Last month, the Lower Kootenay Band stated that it had located the remains of 182 people in unmarked graves. This was near the Kootenay Indian Residential School, also known as the St. Eugene's Mission Residential School, near Cranbrook.

Like the Kuper Island school, the Kootenay and Kamloops schools were operated by the Missionary Oblates of Mary Immaculate through much of their history.

In addition, this Catholic congregation operated the former Marieval Indian Residential School in southern Saskatchewan. That's where the Cowessess First Nation revealed last month that 751 unmarked graves had been located.

According to Chief Cadmus Delorme, there is a margin of error of 10 to 15 percent in this estimate.

CBC News has reported that the Missionary Oblates of Mary Immaculate operated 48 Indian residential schools in Canada.

About 150,000 Indigenous students attended residential schools, which existed in Canada from 1883 until the last one closed in 1996.

They were prohibited from speaking their Indigenous languages or from engaging in traditional cultural practices.

Many were sexually abused and thousands died in what the Truth and Reconciliation Commission of Canada described as "cultural genocide".

The TRC documented 3,213 deaths but the actual number could be as high as 25,0000, according to the former chair, Murray Sinclair.