A grandmother remains in a critical condition in hospital after an out-of-control car pinned her against a fence at a netball court south of Sydney.

The 65-year-old woman and her husband, who is the same age, were struck by the car around 10am yesterday at the Bellingara courts in Miranda, where they had arrived to watch their granddaughter's game.

Judy McLachlan from the Sutherland Shire Netball Association told 9NEWS witnesses screamed before 10 men jumped into action to save the grandfather who was underneath the car.

A woman was pinned against the fence after the car hit her. Image: 9News (9news)

A woman is critical and a man suffered serious head injuries. Image: 9News (9news)

The woman became trapped against a fence in the collision, but was freed by shocked onlookers. Picture: 9NEWS (Nine)

"(There was) just a massive bang, and then screams," she said.

"The ten blokes lifted the car and pulled the person out that was pinned underneath (the vehicle)."

"They were also able to pull the fence away to help free her."

A woman drove her car into the fence of a south Sydney netball court, injuring two pedestrians. Image: 9News (9NEWS)

Ms McLachlan also said the netball court fence the woman was pinned against had young players warming up against it just moments earlier.

"There was a little girl leaning against the fence and she was catapulted off that," she said.

“There are a lot of traumatised kids and parents over what happened.

The driver of the vehicle is now assisting police with enquiries. Picture: 9NEWS. (9NEWS)

“For people to lift a car and pull someone out from underneath, that’s amazing."

The grandparents remain at St Georges Hospital, with the woman in a critical condition.

"Being able to get that treatment to the people straight away makes a big difference," NSW Police Inspector Gary Ford said.

Police are investigating after a car ploughed into two pedestrians south of Sydney today. Image: 9NEWS (NIne)

"There were people everywhere, but luckily the fence in place was able to save any injuries to any of the children."

Sutherland Shire mayor, Carmelo Pesce thanked the emergency services and the local netball community for their quick thinking.

"My thoughts are with the victims of this tragic incident this morning," he said.

The driver is assisting police with their enquiries.