The slide came down 15 kilometres south of Lillooet. It's unclear when the highway will be reopened.
Drivers can check DriveBC for updates.
The highway was closed yesterday after a large boulder landed on the route on Sunday, blocking an entire lane about 10 kilometres north of Lytton. The boulder was blown up by crews on Monday afternoon.
Earlier this month a crash in the area on Highway 99 north of Lillooet killed two people and injured three others, leading to calls for improvements on the route.
Google Maps: Lillooet, B.C.