The crash occurred at about 8:15 p.m. when the driver lost control while taking a curve. He was transported by helicopter to University Hospital for treatment and his condition is stable.
During a benefit race about 45 minutes later, another driver lost control of his car because of a multi-car crash during a heat race.
His car then went over a guardrail barrier and through a safety fence, hitting five spectators.
The driver, 25-year-old Tyson Russell of Crocker, was not injured.
A helicopter and three ambulances were called to help the injured spectators.
A Columbia man, 57-year-old Mark Quisenberry, 57, was transported by helicopter to University Hospital for serious injuries. His condition is stable.
Two people from California, Mo. sustained moderate injuries. Lela Wood, 34, was taken by Staff For Life helicopter to University Hospital, while 27-year-old Jessalin Degonia was transported by ambulance to Bothwell Hospital in Sedalia, Mo. Both were expected to be released from the hospital Monday afternoon.
Two men, 46-year-old Barry Smith of Florence, Mo., and 67-year-old Archie Simpson of Columbia, Mo., had minor injuries. They were treated and released at the scene.
Sunday was Law Enforcement Day at the fair. For the grand finale, old police cars were being used in The Battle of the Badges, an event that raises money for the Special Olympics.
The Missouri Highway Patrol is investigating the second crash.