Four people have been killed and several injured in a school shooting in the western Canadian province of Saskatchewan, police say.
They say a male suspect is now in custody and children have been moved to safety after the shooting at La Loche Community School.
Earlier reports said five people had been killed.
What unfolded in the school was "every parent's worst nightmare", Canadian Prime Minister Justin Trudeau said.
Witnesses at the scene described screaming and more than half a dozen shots.
'Shock and sorrow'
At a news conference, Maureen Levy, a senior officer at the Royal Canadian Mounted Police (RCMP), said the suspect was in custody after his gun was seized.
"There's no risk to public safety at this time," she said, adding: "This is truly a tragedy."
She provided no further details.
Police are also investigating a second shooting at another location in the remote community.
Speaking earlier in Davos, Switzerland, Trudeau said: "Obviously, this is every parent's worst nightmare and all of us across this country - hearts are going out to the families and to the whole community.
Trudeau also praised "the first responders who acted quickly and bravely".
RCMP said they were called about "an active shooter" at 13:00 local times (19:00 GMT) and detained the suspect 45 minutes later, Canada's CBC broadcaster reports.
"Words cannot express my shock and sorrow at the horrific events today in La Loche," Brad Wall, the premier of Saskatchewan, said in a statement.
"My thoughts and prayers are with all the victims, their families and friends and all the people of the community."
About 900 students attend La Loche Community School for kindergarten through to grade 12 (the last year of high school).
"I ran outside the school," Noel Desjarlais, a Grade 10 student, told CBC.
"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."
La Loche is an aboriginal community of about 3,000 people.
It is located about 500km (311 miles) north-west of the city of Prince Albert.
This is said to be Canada's worst school shooting since 14 people were killed by a gunman at Montreal's Ecole Polytechnique in 1989.