The semi-truck involved in Thursday's accident with a bus that killed 15 people in Manitoba, Canada, had the right of way at the time of the incident, according to the Royal Canadian Mounted Police.

Dash camera video taken from the tractor-trailer showed the bus, full of senior citizens, had entered the roadway when the truck had the right of way, superintendent Rob Lasson of the RCMP said in a Friday news conference.

Officials have not determined yet why the bus turned into the lane, Lasson said.

"We are not assigning culpability or laying any blame at this time, we are merely stating the facts as we know them," he said.

The bus was headed south on Highway 5 toward a casino near the town of Carberry, while the semitrailer was headed east on Highway 1, Lasson said Friday.

The semitrailer struck the bus at the intersection of the two highways north of Carberry, roughly 170 kilometers (105 miles) west of Winnipeg.

"Immediately it became apparent that this was a mass casualty situation," Lasson said.

Twenty-five people were on the bus, including the driver, and were between the ages of 58 and 88, according to Lasson. Of those who died, 13 were female and two were male.

In addition to the 15 killed, 10 others were taken to a hospital, authorities said, including the drivers of the semi-truck and the bus.

On Friday evening, the driver of the semi-truck was released from the hospital and is doing well, Lasson said. The driver of the bus was still recovering in the hospital.

Twelve ambulances responded to the collision scene, as well as an air ambulance, said Jennifer Cumpsty, executive director of Acute Health Services.

Manitoba has not seen a mass casualty traffic accident like this before, Lasson told reporters. However, he said, the fatal incident resembles the deadly bus crash over 300 miles away in Canada's Saskatchewan province where 10 Humboldt Broncos hockey players and five others, including two coaches, died in 2018.

"This incident does have echoes of the tragic collision that happened in Humboldt, Saskatchewan," Lasson said. "And we are very much aware of that."

Manitoba RCMP have connected with some of the main investigators in the Humboldt crash for assistance.

"This is new for us and our investigators, and it is very emotionally draining for them as well," Lasson said.

A majority of those on the bus were seniors who lived in and around the city of Dauphin, according to RCMP assistant commissioner Rob Hill.

Flags have been lowered in mourning at Manitoba's legislative building, and Prime Minister Justin Trudeau marked the tragedy in a statement on Twitter.

"The news from Carberry, Manitoba is incredibly tragic. I'm sending my deepest condolences to those who lost loved ones today, and I'm keeping the injured in my thoughts. I cannot imagine the pain those affected are feeling -- but Canadians are here for you," Trudeau tweeted.

William Doherty, CEO of shipping company Day & Ross, which operated the semitrailer, has promised full cooperation with the investigation, noting that "at this time, we have limited details from the scene."