CMS vice president of communications Scott Cooper said after the yesterday's race that all three fans were treated and released from the hospital. He said he couldn't discuss the nature of their injuries due to privacy laws.
Cooper said seven other people were treated with minor cuts and scrapes at the track and released.
Broadcaster Fox Sports said the camera system consists of three ropes -- a drive rope that moves the camera back and forth, and two guide ropes on either side. Fox said it was the drive rope that failed near the first-turn connection and fell to the track.
"We certainly regret that the system failure affected tonight's event, we apologize to the racers whose cars were damaged, and our immediate concern is for the race fans."
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The incident occurred on lap 121 of the 400-lap NASCAR Sprint Cup race, delaying the race for 27 minutes while crews repaired damage to their cars.
Kyle Busch, going for a sweep at Charlotte Motor Speedway after winning the Nationwide and Truck series races, was leading when he incurred damage to the right front wheel well of his No. 18 Toyota.
The cars were initially brought along pit row as workers cleared the ropes from the track.
NASCAR first threw a caution flag before two red flags came out. It eventually allowed the cars to come into the pits, giving crews 15 minutes to work on their cars.
Busch remained competitive and was running in the top five at the midpoint of the race. But his night ended in frustration when his engine blew up on lap 253.
"I commend NASCAR for taking the initiative and letting us repair our damaged cars from the issue we had," Busch said. Busch said he never saw the nylon rope.