TORONTO (REUTERS) - At least four people were killed and two critically injured in a school shooting in a remote part of Saskatchewan on Friday (Jan 22) and a male suspect is in custody, the Canadian police said.

Chief Bobby Cameron of the Federation of Saskatchewan Indian Nations, which represents more than 70 of the province's Indian bands, said a few students were in surgery Friday evening in Saskatoon, the province's largest city.

"Everyone is still in shock and disbelief," Mr Cameron said."It's a very, very horribly tragic event."

A teacher and a teacher's assistant were among the four killed, said Mr Cameron after talking with community members.

The town's Acting Mayor Kevin Janvier told the Associated Press that his 23-year-old daughter Marie, a teacher, was shot to death.

He also said police told him that the gunman first shot two of his siblings at home and then made his way to the school.

A family friend said the teenaged suspect shot his two younger brothers before going to the school and shooting a teacher and an assistant.

"After he shot his two brothers, he walked back to school and he shot ... a teacher and a girl. They're both dead. Four of them died," said Mr Joe Lemaigre, a family friend who lives on the outskirts of La Loche. "I know the family. Their mother worked in Fort McMurray and his grandfather went to Meadow Lake to do some shopping. That's when he shot them."

Officials have not given a motivation for the shooting in La Loche, about 600km north of the city of Saskatoon.

But La Loche acting Mayor Kevin Janvier told the Canadian Press the incident may have started at the suspect's home. "I'm not 100 per cent sure what's actually happened but it started at home and ended at the school," Mr Janvier said.

Mass shootings are relatively rare in Canada, which has stricter gun laws than the United States. With five dead, La Loche would be the country's worst school shooting since 14 college students were killed at Montreal's Ecole Polytechnique in 1989.

"Obviously this is every parent's worst nightmare," said Canadian Prime Minister Justin Trudeau, who was in Davos, Switzerland for the annual World Economic Forum. He had initially reported that five people were killed.

The latest shooting occurred in the high school, called the Dene Building, and another location in Saskatchewan, Mr Trudeau and the Canadian police said. Police took the suspect into custody outside the school and seized a gun.

The shooting occurred in building that houses middle school and high school students, according to the Facebook page of the district, which has about 900 students.

Mr Teddy Clark, chief of the Clearwater River Dene Nation, said his daughter told him about the shooting, the Canadian Broadcasting Corporation reported. "We're just trying to pull together here and make sense of all this," Mr Clark told CBC television. "It's not a very pretty scene right now."

La Loche Grade 10 student Noel Desjarlais told the CBC that he heard multiple shots fired at the school.

"I ran outside the school," Desjarlais said. "There was lots of screaming, there was about six, seven shots before I got outside. I believe there was more shots by the time I did get out."

A cellphone video taken by one resident and broadcast by the CBC showed students walking away from the school through the snow-covered ground and emergency personal moving in.

Extra doctors and nurses were sent to treat patients in Keewatin Yatthe Regional Health Authority's 16-bed hospital, said spokesman Dale West. He declined to say how many people had been injured.

"It's really sad in La Loche today, very depressing," said Ms Tenisha Lemaigre, who lives in the town of less than 3,000 people and said she knew many students.

Unemployment runs above 20 per cent in the area but three-quarters of working-aged people are classified as retired or not looking for work, according to 2011 government figures. Residents say the real unemployment rate is above 50 per cent.

La Loche Community School is a pre-kindergarten to Grade 12 school, which houses about 900 students in two buildings.

There was an emergency at the building that houses grades 7 to 12, the school district's Facebook page said earlier. Both that building and the elementary school were put on lockdown.

"There is currently an emergency occurring at the Dene Building and we are asking the public to stay away while the matter is resolved by the RCMP," the school's Facebook post said earlier.

"The elementary school is also under a lockdown which will not be lifted until we hear that it is safe from the La Loche RCMP. We will not be allowing anyone in or out until we have a clear idea of what is going on."

RCMP is the Royal Canadian Mounted Police.

Saskatchewan Premier Brad Wall issued a statement on the shooting but it did not contain details. "Words cannot express my shock and sorrow at the horrific events today in La Loche. My thoughts and prayers are with all the victims, their families and friends and all the people of the community," the statement said.

In 2014, a teacher expressed concern about violence at the La Loche school, noting that a student who had tried to stab her was put back in her classroom after serving his sentence, and another attacked her at her home.

"That student got 10 months," Ms Janice Wilson told the CBC of the student who tried to stab her in class. "And when he was released he was returned to the school and was put in my classroom."