The vehicle plunged down a steep embankment about six kilometers west of Sutton Pass Wednesday evening.
A deadly single vehicle collision on Hwy 4 Wednesday evening, has claimed the life of a 28 year old man.
Port Alberni RCMP report the crash happened at 8:25pm, about six kilometres west of Sutton Pass.
Police say a vehicle carrying four people plunged down a steep embankment, and hit a tree.
Investigators say two adults weren't wearing seatbelts, and two childen weren't in car seats.
The 25 year old female driver and a child, 3, have serious injuries.
The fourth passenger, a girl, 6, has minor injuries.
The investigation continues into what caused the driver to lose control of the vehicle.