A woman from George died on Friday night, following an accident on the N2, near Kabeljous in Jeffrey's Bay.
Police Spokesperson Sergeant Majola Nkohli says it is believed that a Nissan bakkie with a trailer was travelling towards Port Elizabeth when it parked on the roadside with a puncture.
He says a silver Peugeot Hatchback, travelling in the same direction, swerved to avoid the trailer and lost control.
The car veered off the road and rolled.
One of the passengers, a 46-year-old woman, died on the scene.
Three other people including the driver were taken to a hospital in Humansdorp.
Police are investigating a case of culpable homicide.
