WINDSOR, ONT. -- Caldwell First Nation will begin a 215-hour period of mourning by lowering their flags and wearing orange starting Monday.

The period of mourning and recognition will take place over 215 hours, one hour in honour of each of the 215 children discovered in a mass grave on the site of a former residential school in Kamloops, B.C.

“In addition to being forcibly removed from their families and communities, many children in residential schools faced brutal physical, emotional and sexual abuse, were deprived of food and proper nutrition, and suffered high rates of death. These children were loved and should never have been removed from their families,” an open letter to the Prime Minister says.

In the letter, the Caldwell First Nation has called on Prime Minister Justin Trudeau to lower the country’s flags and declare a National Day of Mourning.

Trudeau announced Sunday the flags would be flown at half-mast on all federal buildings as well as the Peace Tower flag to honour the children as well as survivors and their families.

The City of Windsor will also lower its flags for 215 hours starting Monday in recognition of the victims.

The Caldwell First Nation is encouraging all Canadians to take time to honour the children who suffered in residential schools.