Four people are dead and a 17-year-old boy is facing first-degree murder charges after a shooting in a remote northern Saskatchewan community.

RCMP announced the charges — which include four counts of first-degree murder, seven counts of attempted murder and a single count of unauthorized possession of a firearm — against the teen on Saturday, one day after the shooting in La Loche.

Mounties say officers received several calls from teachers and students at the Dene high school shortly after 1 p.m. Friday. A gunman was firing shots at people in the school and people were injured, callers reported.

Police were able to arrest an armed suspect and seize a firearm after a chase through the school.

Police were then called to a home in the town where officers found the bodies of two teenagers — Dayne Fontaine, 17, and Drayden Fontaine, 13.

Nine staff and students were shot at the school, RCMP said. Marie Janvier, a 21-year-old teacher’s aide, died at the scene while 35-year-old Adam Wood, a teacher, died in hospital.

Initial reports Friday indicated five people were killed and two others were critically injured, but RCMP later corrected the death toll to four victims.

Prime Minister Justin Trudeau, speaking Friday afternoon from Davos, Switzerland, said the commissioner of the RCMP advised him of the situation.

“We all grieve with and stand with the community of La Loche and the province of Saskatchewan on this terrible and tragic day,” Trudeau said. “Obviously this is every parent’s worst nightmare.”

Premier Brad Wall issued a statement expressing shock and sorrow at what he called "the horrific events,” and Bruce Heyman, the U.S. ambassador to Canada, also sent a message of condolence.

"We have experienced similar tragedies far too often in the United States and understand all too well the heartache and sadness that result from such a horrific event," Heyman said.

"Our thoughts and prayers remain with the victims and their families, the community of La Loche, the residents of Saskatchewan, and all Canadians during this most difficult time."

La Loche, a remote Dene community of about 3,000 people on the eastern shore of Lac La Loche in the northern boreal forest, is located about 600 kilometres north of Saskatoon.

About 900 students attend two schools in the town, and according to RCMP, about 150 were in the high school at the time of the shooting.

Four of the nine people shot in the school were taken to Royal University Hospital in Saskatoon via STARS air ambulance, Mounties said Saturday. Three others were taken to La Loche Health Centre and are set to be transported to Saskatoon when weather conditions permit.

Investigators were still on scene at both the high school and the home, and candles from a Friday night vigil for the victims were still burning, Saturday morning.

The accused cannot be named under the Youth Criminal Justice Act.

--- with files from The Canadian Press and CTVNews.ca