A 68-year-old Agassiz woman was seriously injured after her vehicle left Highway 9 near the Highway 7 intersection at about 8:30 a.m. Monday.
RCMP investigators are not releasing her name.
The woman driving a brown Ford Taurus allegedly failed to yield to a green Pontiac Grand Prix already travelling southbound on Highway 9 where it changes from Highway 7.
"The driver of the Ford Taurus swerved to avoid a collision with the other car, but then went off road right into the ditch," RCMP Cpl. Peter Thiessen said.
"The Ford landed on its roof, trapping the driver and sole occupant," he said.
Firefighters worked to free the seriously injured driver, and BC Ambulance paramedics airlifted her to the Royal Columbian Hospital in New Westminster.
An investigation by the RCMP's Fraser Valley Traffic Services continues.
