FIVE children, aged from four to 15-years-old, have been injured after a car ploughed into the crowd at a mud-racing event in Victoria.

The crash happened just after 4pm during The Mud Run, an event being held at Dalyston Recreation Reserve near Wonthaggi in southeast Victoria, a police spokeswoman said.

"It's vehicles racing around a mud track," she said.

"One of the cars has lost control and veered into the crowd."

An Ambulance Victoria spokesman said paramedics had treated five children at the scene and they were being taken to hospitals both nearby and in Melbourne.

A four-year-old-boy with multiple fractures, a 10-year-old girl with a broken leg and a 15-year-old girl, also with a broken leg, were being taken via air ambulance to the Royal Children's Hospital.

An eight-year-old boy with knee injuries was being taken to Wonthaggi Hospital and a nine-year-old girl with hip injuries was being transported to Dandenong Hospital.

The spokesman said all the children were in a serious but stable condition.

He said paramedics were still on scene checking if anyone else needed medical attention.

The event was organised by the Australian 4WD Mud Racing Association.