TORONTO – A gunman opened fire at a high school and a second location in an aboriginal community in northern Saskatchewan on Friday, leaving four dead and at least two injured, officials said.

Prime Minister Justin Trudeau said from Davos, Switzerland, that a suspect was in custody.

“This is every parent’s worst nightmare,” he said. “The community is reeling.”

Kevin Janvier told the Associated Press that his 23-year old daughter, Marie, a teacher, was shot dead by the gunman. He said police told him the gunman first shot two of his own siblings before killing Janvier’s daughter.

“He shot two of his brothers at his home and made his way to the school,” he said.

“I’m just so sad.”

Marie was Janvier’s only child. He said he didn’t know if the shooter knew his daughter.

Royal Canadian Mounted Police Chief Superintendent Maureen Levy said the gunman was arrested outside the school but declined to release details about him.

Levy said she wasn’t sure how many suffered injuries. The prime minister earlier described two injuries as critical.

Levy declined to release more details, saying the investigation is in its early stages. She declined to give the sex or ages of the deceased.

A student who was just returning from lunch when shots were fired said his friends ran past him urging him to get out.

“‘Run, bro, run!” Noel Desjarlais-Thomas, 16, recalled his friends saying to him as they fled La Loche’s junior and senior high school.

“There’s a shotgun! There’s a shotgun! They were just yelling to me. And then I was hearing those shots, too, so of course I started running.”

The grade seven through 12 La Loche Community School is in the remote Dene aboriginal community of La Loche, Saskatchewan.

Bobby Cameron, chief of the Federation of Saskatchewan Indian Nations, said it was the worst tragedy to hit the community.