Police are investigating a tragic single-vehicle crash that killed a baby and left two others seriously injured in Perth’s south-east overnight.

A silver Toyota Kluger was travelling along Nicholson Road in Lynwood around 3.40am when it veered off the wet road and into a bus stop before hitting a tree, police said.

Three passengers – a 32-year-old woman, a seven-month-old baby and a three-year-old child – were all seriously injured in the crash.

Lynwood fatal A silver Toyota Kluger was travelling along Nicholson Road in Lynwood around 3.40am when it veered off the road and hit a tree, police said. (Nine)

Neighbours have told 9News several people rushed to help the woman who got out of the car with the baby, witnesses giving the infant CPR.

The woman and the seven-month-old were rushed to Fiona Stanley Hospital, where the baby sadly died.

The three-year-old was taken to Perth Children’s Hospital with serious injuries.

A 35-year-old man, who is a rideshare driver, sustained minor injuries.

Police are now investigating if the children were secured in booster seats, which is not a legal requirement for taxis and rideshare vehicles in WA.

Lynwood fatal Neighbours have told 9News several people rushed to help the woman who got out of the car with the baby, witnesses giving the infant CPR. (Nine)

Anyone who may have witnessed the crash, or saw the silver Kluger travelling in the area beforehand, is urged to contact police.

Anyone with dashcam or mobile phone vision relating to this crash can upload it directly to investigators via this link.