Nine people were injured, one critically, after a car crashed into a crowd during a demolition derby in southeastern Australia, police said.

The car had been taking part in a race in the town of Walcha on Saturday night when it drove through a fence and hit the grandstand, New South Wales police said in a statement.

The race, part of the annual Walcha Motorcycle Rally, had been a demolition derby - a type of motorsport where drivers ram their vehicles into one another.

Police said ages of the injured bystanders ranged from 20 to 75, while the critically injured person was a 54-year-old man. An investigation was underway, they said.

Police said they were told that the 27-year-old driver of the car had been involved in a collision on the track right before it drove into the fence.