Canadian police said the truck driver was initially detained but has since been released and provided with mental health assistance. Royal Canadian Mounted Police Assistant Commissioner Curtis Zablocki said it's too early to state a cause for the crash.
In a tweet, US President Donald Trump said he called Trudeau to offer his condolences to the families.
Darren Opp, president of the Nipawin Hawks, said a semi T-boned the players' bus - an account police confirmed. "It's a horrible accident, my God," Opp said.
Hassan Masri, an emergency room doctor at Saskatoon's Royal University Hospital who has done work in war-torn Syria, said the crash reminded him of an airstrike.
Photographs of the wreckage showed the twisted trailer with most of its wheels in the air and the bus on its side and its back portion destroyed. The force of the crash sent both vehicles into the ditch at the northwest corner of the intersection.
Aerial footage showed the bus on its side, its roof peeled back and its front end destroyed. The trailer of the truck lay nearby in a shattered mess, with bags of its peat moss cargo scattered all around. The tractor part of the truck was intact, lying on its passenger side.
The tractor-trailer would have had to yield to a stop sign before crossing over the highway that the hockey bus was travelling on. There is a stand of trees on the southeast corner of the intersection, limiting visibility of the approach on both roads.
Police said a lot of issues have to be investigated, including weather conditions at the time and any mechanical issues with the vehicles.
The Humboldt Broncos are from Humboldt, Saskatchewan, which has a population of about 6000. Many gathered at the community centre at the hockey arena there after word of the horrific crash began to circulate.
Humboldt Mayor Rob Muench, wearing a Broncos team jersey, hugged people as they came to the Elger Petersen Arena in the Saskatchewan town to comfort each other and learn more. "It's overwhelming. It's been tough on everybody," Muench said. "We're a small community; some of those kids have been on the team for a number of years. A lot grew up in the community and everybody knows each other."
- AP