Drag racing fanatics have defended their high-octane sport after an eight-year-old girl was critically injured when the machine she was driving crashed today at the Perth Motorplex at Kwinana.

It is believed the girl, whose name has not been released, lost control of the dragster just before 2pm and slammed into a wall near an exit gate.

The impact was so great she had to be revived at the crash scene by paramedics who were on duty at the event.

An ambulance spokesman said she was taken to Rockingham Hospital before being transferred to Princess Margaret Hospital in a critical condition.

Camera Icon An ambulance arrives at the emergency department at Princess Margaret Hospital. Credit: WORDPRESS

Those who witnessed the incident comfort each other outside the Kwinana Motorplex.

It is believed the girl was attempting to do a solo drive, which is required for young drag racers wanting to be licensed and then compete in future events.

VenuesWest confirmed that no other vehicles were involved and that it was helping WA Police investigate the incident.

The girl comes from a drag racing family and their Facebook page has numerous videos and posts of the young girl in and around drag cars.

One video shows the girl practising her drag starts out of the family’s garage under the watchful eye of her father.

On its Facebook page, Perth Motorplex said police attended and on their advice racing was suspended.

Mike Sprlyan, of Junior Dragster Australia, said it was not unusual for an eight-year-old to get behind the wheel.

Camera Icon Those who witnessed the incident comfort each other outside the Kwinana Motorplex. Credit: WORDPRESS

He said competitors in junior drag racing ranged in age from 8 to 17 and were placed in three classes depending on experience.

The beginners drive what are known as "tin pots" that can reach top speeds of 40-50km/h, he said.

He said the injured girl would have only driven "half track" as she was only participating in a solo pass to obtain her licence. It’s not known if this was the first time she had driven at Motorplex.

Motorplex reopened the track and racing resumed just after 5pm.

A statement issued by the venue said police had "completed their investigations".

"We thank all patrons and participants for their patience and understanding. Our thoughts are with the driver and family," the statement said.