The Humboldt Broncos were travelling on Highway 35, north of Tisdale in the province of Saskatchewan.
The Royal Canadian Mounted Police said 28 people were on the bus, 14 of whom were killed, including the driver.
The other 14 aboard the bus have been taken to hospital. Three are in critical condition.
In a tweet, Prime Minister Justin Trudeau wrote: "I cannot imagine what these parents are going through".
The lorry and the bus collided at around 17:00 local time (23:00 GMT).
The Humboldt Broncos, who play in the Saskatchewan Junior Hockey League, were en route to a play-off game against the Nipawin Hawks.
Their team list shows the players are aged between 16 and 21.
Royal Canadian Mounted Police inspector Ted Munro said rescue efforts were ongoing and that they had set up an information and support centre for families at the Nipawin Apostolic Church.
"Our thoughts and prayers are with the families tonight," he said.
Myles Shumlanski, father to one of the Broncos players, arrived at the scene after a call from his son.
"It was a disaster," he told the Saskatoon Star Phoenix paper. "We had a crane lifting the bus."
Team president Kevin Garinger released a statement extending "our thoughts and prayers" to the families of staff and athletes.
"Our Broncos family is in shock as we try to come to grips with our incredible loss."
Darren Opp, the president of the Nipawin Hawks, told the Globe and Mail: "It's a horrible accident, my God, it's very, very bad.
"There's uncles and moms and dads waiting to hear whether their sons and nephews are OK."
BBC
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