Indigenous groups in Canada have demanded a nationwide search for further graves after the discovery of the remains of 215 children. The Tk'emlups te Secwepemc First Nation announced last week that remains were found at a former residential school set up to assimilate indigenous people. The find sparked outrage, prompting some in Canada to lay out tiny shoes at makeshift memorials. Prime Minister Justin Trudeau pledged help but gave few details. "As a dad, I can't imagine what it would feel like to have my kids taken away from me," Mr Trudeau told reporters. "And as prime minister, I am appalled by the shameful policy that stole indigenous children from their communities." While he promised "concrete action" when asked what the government would do he did not offer specific commitments. On Monday, Mr Trudeau released a statement marking the start of National Indigenous History Month, noting that the "heartbreaking discovery" in Kamloops last week "is not an exception or isolated incident". Opposition New Democratic Party leader Jagmeet Singh on Monday also called for an emergency debate among lawmakers. "Anytime we think about unmarked mass graves, we think about a distant country where a genocide has happened," he said. "This is not a distant country." Perry Bellegarde, national chief of the Assembly of First Nations, said in a statement the families "deserve to know the truth and the opportunity to heal". "A thorough investigation into all former residential school sites could lead to more truths of the genocide against our people," Mr Bellegarde said. The University of British Columbia (UBC) said in a statement it would meet on Monday to review a 1986 doctorate the school granted Roman Catholic Bishop John Fergus O'Grady - once the principal of the residential school where the children's remains were found. "Universities, including UBC, bear part of the responsibility for this history," the university said of residential schools. "Our commitment is to learn from our mistakes." In Charlottetown on Prince Edward Island, a statue of Canada's first Prime Minister, John A Macdonald, is being removed following the discovery of the children's remains. Macdonald's role in residential schools has made him a target for protesters.