Officers from Chifley Police District attended, along with three NSW Ambulance paramedic road crews and a rescue helicopter.

The pedestrian, a 29-year-old woman, was treated for head and shoulder injuries and taken to Westmead Hospital. The one-year-old child was also assessed for suspected internal injuries before being airlifted to the Children's Hospital at Westmead for observations.

Both patients were in a serious but stable condition.

The driver, a 73-year-old woman, was subjected to a road-side breath test, returning a negative result. She was taken to Lithgow Hospital suffering shock.

NSW Ambulance A/Inspector Lochlan Rush said the initial call suggested a pram had been struck and thrown several metres by a car which has the potential to cause terrible injuries.

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"Paramedics stabilised the patients on scene before both were taken to hospital, the young child was transported in the rescue helicopter," he said.

"Incidents like this are a reminder to take care and slow down in high pedestrian areas."

Police closed off Main Street at the James Street, Hassans Walls Road and Ferro Street intersections with a heavy flow of east bound traffic including railway buses and semi trailers diverted into Ferro Street.

A crime scene was established and examined by specialist officers attached to the Metropolitan Crash Investigation Unit.

An investigation is underway into the circumstances surrounding the crash.

Inquiries continue.

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