The Saskatoon StarPhoenix said 14 more were injured – including three critically – in Friday's accident involving the Humboldt Broncos team bus.
The bus was carrying 28 people, including the driver.
Police said the crash took place at around 5:00 pm local time about 28 kilometres north of the town of Tisdale, a trading centre in an overwhelmingly agricultural region.
Journalist Chris Vandenbreekel was at the crash site.
The team was heading north for a Saskatchewan Junior Hockey League playoff game against the Nipawin Hawks.
The Saskatchewan league is a feeder system for higher levels of hockey with many graduating to play at US and Canadian colleges and major junior league level, while some go on to the National Hockey League.
"It is a significant accident, we had a tractor-trailer and a bus collide," Royal Canadian Mounted Police inspector Ted Munro told reporters, declining to go into further detail about the victims.
The condition of the truck's driver is unknown. The Saskatchewan Health Authority said on Twitter it was dealing with a "high volume of incoming trauma cases" at Royal University Hospital and St Paul's Hospital, both located in Saskatoon some 250 kilometres away from the crash site.
Victims' families were directed to Nipawin Apostolic Church for information and support.
"Our Broncos family is in shock as we try to come to grips with our incredible loss," Broncos team president Kevin Garinger said in a statement.
The team comprises 24 players, all from Canada, with the youngest aged 16 and the oldest 21.
Canadian Prime Minister Justin Trudeau said: "I cannot imagine what these parents are going through, and my heart goes out to everyone affected by this terrible tragedy, in the Humboldt community and beyond."
Friday's fatal smash brought back memories of a single vehicle bus crash in December 1986, also in Saskatchewan, that killed four members of the Western Hockey League Swift Current Broncos.
The Swift Current Broncos shared their condolences.
"Humboldt Broncos weighing heavy in our hearts and minds tonight," the team said on Twitter.