Four people were taken to hospital following a serious accident on the Coquihalla highway on Saturday.
British Columbia Emergency Health Services said they were called about a single vehicle rollover around 8:30 a.m.
Two people were taken to hospital in critical condition, while two others were taken to stable.
The highway was closed to southbound traffic until about 3:45 p.m., and DriveBC has warned area travelers to continue to expect significant delays due to congestion.
Route 1 remains closed in both directions between Lytton and Hope due to firefighting efforts, likely exacerbating delays caused by the Coquihalla closure.