Squamish RCMP are investigating a deadly crash on the Sea-to-Sky Highway that snarled traffic Sunday afternoon.

The three-vehicle collision happened about 10 km south of Whistler just before noon.

Officers arrived at the scene and determined one person had died. RCMP have not specified the injuries of the other occupants.

Insp. Dale Carr with the Lower Mainland District RCMP said the initial investigation reveals a driver crossed the centre line and collided head-on with another vehicle.

"Our goal now is to gather the evidence as quickly as we can, as safely as we can, and then get that highway open to fully operational," Carr said.

Drive BC reported the one lane was reopened to alternating traffic around 1:45 p.m.

It's estimated the road will be fully reopened at 6 p.m.