The slain were identified as Adam Wood, 35, a teacher at La Loche Community School
; Marie Janvier, 21, a teacher's aide; and brothers Dayne Fontaine, 17, and and Drayden Fontaine, 13. They were residents of La Loche.
La Loche, located about 605 kilometers (375 miles) from Saskatoon, has about 2,600 residents, most of them Native American members of the Dene Nation
. Everybody knows everybody else, so the slayings were traumatic.
"Every individual in La Loche has been wounded by this event," acting Mayor Kevin Janvier said at a press conference. "These emotional and mental wounds... will take years to heal. The most sorrowing and disastrous event has happened here, in the place where people should have felt safest, in our schools."
Royal Canadian Mounted Police said a 17-year-old boy walked into the school Friday afternoon with a gun and started shooting. They would not identify the suspect because of his age.
Police arrived, chased the shooter through the school and arrested him at gunpoint, said RCMP Superintendent Grant St. Germaine.
Police found nine people shot. One person died at the scene and another was taken to the local hospital, where he was pronounced dead, St. Germaine said. Seven others were wounded and taken to the local hospital or University Hospital in Saskatoon for treatment.
'A silent guy'
A little later, officers heard about another incident at a nearby residence. When police went inside, they found the two Fontaine brothers dead.
St. Germaine said he didn't know the motive for the killings or whether the suspect was a student. The teen will appear in court next week. He is charged with four counts of first-degree murder, seven counts of attempted murder and unlawful possession of a firearm.
Student Jackson Janvier, 15, described the suspect as "a silent guy," according to CNN affiliate CBC.
"You barely see him around," Janvier said. "He went for school or would go for bike rides with us at times. He was just a silent quiet guy. He doesn't talk about anything. He just sits there or walks around with us."
Janvier said he was at the school on Friday and saw one person shot.
"Right when he walked in he took that shot, no second thoughts -- he just shot him," Janvier told CBC. "Then I started running. I heard like five more shots before I got out of the school."
Shooter looked 'a little stressed'
Student Darius Piche, 17, told CBC he saw the suspect walk into the building looking "a little stressed." When Piche asked what was wrong, the suspect walked back outside and grabbed a gun from his vehicle, Piche said.
"I ran back inside, I told everyone to 'Run, he has a gun,' " Piche said. "While the lockdown was happening, you could just hear all these gunshots getting closer, [then] getting distant."
Clearwater River Dene Nation Chief Teddy Clark described the shooting as devastating.
"Both Clearwater and La Loche, a lot of people are in shock. This is something that you only see on TV most of the time," Clark told the Star Phoenix newspaper.
The school teaches prekindergarten to 12th grade and houses about 900 students in two buildings, its Facebook page says.