Police were called to the area of Surrey Lake Summit around 3:15 p.m. PT Monday afternoon.
Const. Steven Grouhel says when he arrived he found two vehicles, one on its side and another upright. Witnesses told him both crashed separately just a few metres and a few minutes apart.
"At the time of the crash witnesses said it was an extreme downpour of rain with thunder and I guess the highway was just covered in water, like a river," he said.
Both drivers were taken to hospital in Kamloops and are in stable condition.