In a show of solidarity for the community of La Loche, Sask., people are changing their Facebook photos to an image of a blue ribbon with white trim.

The image is spreading online after a shooting at two locations, including a school, in the northern Saskatchewan community.

Four people were killed and seven others were critically injured during the shootings on Friday.

Blue Ribbon for La Loche, Sask.

In a show of solidarity for the community of La Loche, Sask., people are changing their Facebook photos to an image of a blue ribbon. (Facebook)

On the ribbon image, a message for the community: "Never Forget Dene High School 2016".

"The staff of La Loche Community School and the whole Northern Lights School Division family wish to express their heartfelt condolences to the community of La Loche," read a post on the school's Facebook page Sunday afternoon.

"We share in the grief of the parents, students, friends and colleagues of those we have lost. We will rebuild and continue to pursue healing with our community. God bless us all."

Two of the victims were staff members of the school: Marie Janvier, 21, was an educational assistant at the school and Adam Wood, 35, was a teacher.

The Saskatchewan Teachers' Federation will hold a vigil in Saskatoon Sunday night.

"Regardless of where we teach or live in our province, the tragic events that occurred this week have had an impact on all of us and we are grieving with students, teachers, the family and friends of the victims and the community," STF president Patrick Maze said in a letter to members.

"As colleagues, our hearts go out to all of the dedicated and passionate teachers of La Loche and Northern Lights School Division."

Others reach out in statements of condolences

In a statement, Metis Nation-Saskatchewan President Robert Doucette said the tragedy will go down as one of the saddest days in the province's history.

Assembly of Manitoba Chiefs Grand Chief Derek Nepinak said he had been in the Dene territory in the past and met the "wonderful people". In the statement, he said his heart was heavy with sadness. He said he would be in contact with the Meadow Lake Tribal Council and the Federation of Saskatchewan Indian Nations to provide support in the coming days.