There was an outpouring of grief across Canada at news of the collision between a bus carrying a junior ice hockey team and a semi-trailer.
The Humboldt Broncos team, which has members aged between 16 and 21, were en route on Friday to a play-off game.
At least 15 people have been confirmed dead in the crash.
Details have been slow to trickle out in the wake of the tragedy, and the identities of the deceased have not yet been released by authorities.
Tom Straschnitzki said his son Ryan is in hospital in Saskatoon with a serious back injury, and told his father that he can't feel his legs.
The family flew to his bedside on Saturday to be with him.
"He keeps asking about his team and coaches. I say: I don't know son," he told the BBC from his home in Airdrie, Alberta.
Mr Trudeau said in a statement that "our national hockey family is a close one, with roots in almost every town - small and big - across Canada".
He has received calls of condolences from other world leaders, including US President Donald Trump.
What is known about the crash?
The lorry and bus collided on Friday at around 17:00 local time (23:00 GMT) on Highway 35, north of Tisdale.
The Royal Canadian Mounted Police said 29 people including the driver were on the bus at the time, and that15 people were killed.
The other 15 passengers have been taken to hospital. Two remain in critical condition.
The lorry driver was not injured in the collision.
Police said on Saturday they have yet to determine the cause of the crash.
Myles Shumlanski, father of one of the Broncos players, described the scene as a "disaster" to the Saskatoon Star Phoenix paper. "We had a crane lifting the bus," he said.
It is not yet known who has died. There were ice hockey coaches on the bus in addition to team members.
Photographs on social media showed several of the players comforting each other in hospital.
(A photo posted to the team's Twitter feed on 24 March after a play-off win)