A toddler is critical after being hit by a car in Perth's south-east.

The boy, who is 14 months old, was struck about 10.30 this morning on a suburban street in Maddington.

The child was rushed to Armadale Hospital before he was transferred to Perth Children's Hospital in a critical condition. 

The street has been blocked off for most of the day as West Australian Police continue to gather evidence and speak to witnesses. 

A woman is understood to be helping police with their inquiries.