LA LOCHE, Sask. -- Police say a 17-year-old has been charged with four counts of first-degree murder and seven counts of attempted murder in a mass shooting at a school and home in northern Saskatchewan.

The male can't be named under the Youth Criminal Justice Act.

Police say they were called to the high school in La Loche shortly after the lunch hour on Friday for reports of a shooting.

They say they were able to arrest an armed suspect after a chase through the halls.

Officers found nine staff and students had been shot -- one woman, a teachers' aide, died at the scene while a male teacher died in hospital.

Police were then called to a home in La Loche where they found two teenagers dead.

The dead have been officially identified as Adam Wood, 35, and Marie Janvier, 21, both of whom where shot at the school.

Dayne Fontaine, 17, and Drayden Fontaine, 13, were found dead in the home. Police said they had received consent to name the two teens from family members.

Wood started teaching at the La Loche Community School in September.

His family in Ontario said in a statement that he was an adventurer with a passion for life who made people laugh until their stomachs hurt.

"Adam had just begun his teaching career in La Loche last September and was enjoying his time," the statement reads. "He was always up for a good challenge and lived each day joyously."

Marie Janvier also started working at the school last fall as a classroom aide.

Janvier's friend Ashton Lemaigre said the woman was kind and patient with children and planned to get her teaching degree someday.

"The kids loved having her around," Lemaigre said. "When we were out and about kids would say 'Hi.' They would just come running to her. And she was just a friend to everybody."

Witnesses recalled a terrifying scene of panic as students fled for their lives at the school. Some students said they ran for the doors when they saw a shotgun while others hid in gym dressing rooms for hours after they heard the shots.

One student forwarded to The Canadian Press a screenshot of a chilling exchange that had taken place on social media a short time before the shooting between a young man and his friends.

"Just killed 2 ppl," wrote the young man. "Bout to shoot ip the school."