A woman has been killed and three other people have been seriously injured in a two-car crash in South Australia.

A Mitsubishi ute and Toyota sedan collided just before 8am at the intersection of Church Road and Port Wakefield Highway, at Lower Light near Two Wells, north of Adelaide.

The 55-year-old driver of the Toyota passed away at the scene.

A woman has been killed in a two-car crash in South Australia this morning. A woman has been killed in a two-car crash in South Australia this morning. (Nine)

Locals told 9News the crash was an “awful” tragedy and said the road has gotten dangerous.

“I don’t think it’s as safe as it used to be,” local Judy Dobson said.

“When the dual carriageway went through, they changed the angle of the road.”

The 70-year-old driver of the Mitsubishi and his two passengers, aged 58 and 42 sustained non-life-threatening but serious injuries.

One was airlifted to the Royal Adelaide Hospital with serious injuries, the other two were taken to the hospital in an ambulance. 

A woman has been killed in a two-car crash in South Australia this morning. Locals told 9News the crash was an “awful” tragedy and said the road has gotten more dangerous. (Nine)

Port Wakefield Highway was closed for several hours as the site was cleared.

The road has since reopened.

Anyone who witnessed the crash has been asked to contact Crime Stoppers.