A deadly collision between a semi-trailer truck and a seniors’ minibus on the Trans-Canada Highway near Carberry, Manitoba, left at least 15 people dead and 10 more injured on Thursday, according to Canadian authorities.

The RCMP said they were dealing with a “mass casualty collision” and that multiple units were on the scene, along with first responders and helicopters. Officer Rob Hill said most of the 25 passengers on the bus were elderly.

The crash happened around noon at the intersection of Highway One and Highway Five, north of Carberry. Witnesses reported seeing a burned vehicle in a ditch and tarps covering some of the victims, CBC News said.

Canadian Prime Minister Justin Trudeau and Manitoba Premier Heather Stefanson expressed their condolences to the families of the victims and their support for the survivors. Flags at the Manitoba legislature were lowered to half-staff in honor of those who died.

The cause of the crash is still under investigation and the highway remains closed in both directions. Authorities are asking drivers to avoid the area.

Josh Carson, a truck driver who passed by the site, told Global News it looked like a “pretty bad one” and that some people were receiving medical attention.

The accident is reminiscent of a 2018 tragedy in Saskatchewan, where 15 people died when a truck hit a bus carrying young hockey players.