A horrifying crash on the last lap of a race at Daytona International Speedway has injured at least 30 fans and provided another stark reminder of what can happen when a car going nearly 200 mph is suddenly launched toward the spectator areas.
The victims were sprayed with large chunks of debris - including a tyre - after newcomer Kyle Larson's machine hit fencing that is designed to protect the massive grandstands lining Nascar's most famous track.
"I love the sport," said Shannan Devine, who witnessed the carnage from her 19th-row seat, about 250 feet away. "But no one wants to get hurt over it."
The fencing served its primary purpose, catapulting what was left of Larson's car back on to the track. But it did not keep potentially lethal shards from flying into the stands.
"There was absolute shock," Ms Devine said. "People were saying, 'I can't believe it, I can't believe it. I've never seen this happen, I've never seen this happen. Did the car through the fence?' It was just shock and awe. Grown men were reaching out and grabbing someone, saying, 'Oh my gosh! Oh my gosh!' It was just disbelief, absolute disbelief."
From Daytona to Le Mans to a rural road in Ireland, auto racing spectators have long been too close to the action when parts start flying. The crash in the second-tier Nationwide race follows a long list of accidents that have left fans dead or injured.
The most tragic incident occurred during the 1955 24 Hours of Le Mans, when two cars collided near the main stands. The wreck sent debris hurtling into the crowd, while one of the cars flipped upside down and exploded in a giant fireball.
Eighty-three spectators and driver Pierre Levegh were killed, and 120 fans were injured.
The Daytona crash began as the field approached the checkered flag and leader Regan Smith attempted to block Brad Keselowski. That triggered a chain reaction, and Larson hit the cars in front of him and went airborne into the fence.
The entire front end was sheared off Larson's car, and his burning engine was wedged through a gaping hole in the fence. Chunks of debris from the car were thrown into the stands, including a tyre that cleared the top of the fence and landed midway up the spectator section closest to the track.