Three dead in South Australia crashes

Three people have died in separate crashes in South Australia, including two people who died on the Stuart Highway in the state's far north.

The crash took place between Pimba and Glendambo after midday on Saturday, when a B-double truck collided with a Ford ute.

The driver of the ute, a 23-year-old ACT man, and a passenger in the truck, a 57-year-old woman from Para Vista, died at the scene.

The truck driver, a 49-year-old Para Vista man, remains in a critical condition.

Later on Saturday, a ute rolled over on a private property in Lindley in SA's Riverland, with a 26-year-old man dying at the scene.

Three other people in the car were taken to hospital with non-serious injuries.

"Three people have lost their lives on our roads already this long weekend and police implore all road users to take care, particularly in regional areas, and not take unnecessary risks," SA Police said in a statement.

"Over the past five years, the March long weekend has seen six lives lost on South Australian roads, with five of those being on regional or rural roads."