The plane, piloted by 74-year-old Jimmy Leeward, curved out of control without warning and show fall to pieces upon impact. Bloodied bodies were extending across the area as people tended to the victims and ambulances hurried to the scene.
Establishments were investigating the cause, other than an official with the event said there were signs that mechanical problems were to blame.
Maureen Higgins of Alabama, who has been pending to the air races for 16 years, said the pilot was on his third lap when he missing control.
She was sitting about 30 yards away from the hurtle and watched in horror as the man in front of her started flow of blood after rubbish hit him in the head.