Perth ambulance crash survivor 'lucky to be alive'

A 75-year-old man says he feels lucky to be alive after being inside an ambulance when it was hit and flipped in Perth's south.

Gerald Stokes was being rushed to hospital with an emergency ulcer condition on Wednesday afternoon when another car slammed into the side of the ambulance on Ennis Avenue in Rockingham.

Speaking from his hospital bed in Fiona Stanley Hospital, Mr Stokes says he was knocked unconscious on impact.

"Part of the crash I don't remember. I just remember all the people and firemen standing around me," Mr Stokes said.

The father of two says paramedics had to tell him he'd been in a crash.

"I was still slightly shocked, I didn't understand, I wasn't in any pain. The last vehicle you'd think you be in would be an ambulance," he said.

The driver of the other car wasn't hurt in the crash, neither was the doctor inside the ambulance, but one of the two paramedics suffered a shoulder injury and are now both on medical leave.

"The advice from police at this point of time is they don't know why that occurred or where fault lies," WA Police Minister Michelle Roberts said.

Gerald Stokes is warning other drivers who see an ambulance on the road to slow down.

He's expected to make a full recovery.