A pedestrian and truck driver were killed while another was injured three serious crashes in SA on Christmas Day

A pedestrian and a truck driver have died, while a motorcyclist was seriously injured in three separate horror Christmas Day crashes in SA.

A pedestrian and a truck driver were killed while a motorcyclist suffered serious injuries in three separate horror Christmas Day crashes on South Australian roads.

The first crash happened when a truck crashed and rolled on the Eyre Highway at Lake Gilles on the Eyre Peninsula just after 3pm Saturday.

The truck driver, a St Kitts man, 56, died at the scene.

Major crash investigators visited the scene of every crash, were at the scene and the Eyre Highway was expected to remain closed between Iron Knob and Kimba with detours in place on Sunday.

In the evening, a Suzuki SUV crashed into a pedestrian on the St Vincent Highway at Port Julia, on the Yorke Peninsula about 9.30pm.

The pedestrian, a Marryatville woman, 37, died at the scene.

The driver of the Suzuki, a woman from the Yorke Peninsula, 61, was not injured.

The St Vincent Highway was closed to traffic for several hours but has since reopened.

In another incident, a motorbike and Holden Commodore crashed at the intersection of McKay Ave and Buckingham Court at Windsor Gardens around 7.15pm.

The rider of the bike, a Greenacres man, 31, suffered serious injuries and was rushed to the Royal Adelaide Hospital where he remains.

The driver of the Holden, a Modbury North man, 72, was not injured.

The crashes take the total number of lives lost to 99, compared to 90 at the same time last year.

It follows the death of a driver, 34, who crashed and rolled into a paddock at Greenways, north west of Mt Gambier.

The crash happened on Tuesday, but the man succumbed to his injuries two days later.

Originally published as A pedestrian and truck driver were killed while another was injured three serious crashes in SA on Christmas Day