The bus was carrying around 25 people when the crash happened just before noon on Thursday.
The crash occurred on the Trans-Canada Highway near Carberry, Manitoba in Canada.
Carrying mostly senior passengers, the bus was en route to the Sand Hills Casino in Carberry, a spokesperson for the casino told CTV News.
Royal Canadian Mounted Police said all resources were being sent to the scene.
The crash prompted a mass casualty incident response at hospitals at Health Sciences Centre (HSC) in Winnipeg, CTV News reported.
“Paramedics and first responders spend their entire careers preparing for a day like this, hoping it will never come – today it came,” said Jennifer Cumpsty with HSC.
“All of them did their jobs with the utmost skill and professionalism.”
RCMP Superintendent Rob Lasson said “as of right now the drivers of both the bus and truck are alive and in hospital,” per the AP.
Lasson said that determining who had the right of way will be critical for the crash investigation.
“The public is reeling and asking a lot of questions and people are trying to determine if their loved ones were involved,” Lasson said.
“Death on this scale is never normalized for us.”
Images from the scene showed a still smoldering bus in a ditch.
Debris – which reportedly included a walking aid – was scattered across the highway.
Police also said that many of the passengers on the bus were from Dauphin, a town in Manitoba about two hours north of where the crash occurred.
Kim Armstrong with the Dauphin senior center said the bus left earlier on Thursday morning.
“It’s huge to lose so many individuals of our community and of course it is shocking. We just pray for those that are surviving,” she said, per the AP.
The truck company that owned the semi involved in the crash released a statement.
“We will fully cooperate with the investigation and offer any assistance and support that we can,” said William Doherty, CEO of Day & Ross, per the AP.
Other officials have also spoken out about the crash.
“This is a day in Manitoba and across Canada that will be remembered as one of tragedy and incredible sadness,” Manitoba RCMP Commanding Officer Rob Hill said.
Prime Minister Justin Trudeau echoed those sentiments in a tweet.
“The news from Carberry, Manitoba is incredibly tragic,” he tweeted.
“I’m sending my deepest condolences to those who lost loved ones today, and I’m keeping the injured in my thoughts.”