RCMP say a "serious collision" on Wednesday has closed the Alaska Highway near Rancheria, Yukon, about 320 kilometres east of Whitehorse.
Police expected the highway to be closed to traffic in both directions, for several hours.
No other details about the accident were available. RCMP said just before 5 p.m. that officers were still on their way to the scene.
Police advise motorists to check Yukon511 for updates.