Twenty-five people were injured when an aerial swing ride collapsed and fell approximately 20 feet (6m) at the “Day of the Dead” fair. Source (in Spanish)
Theme parks and roller coasters are statistically very, very, very safe. Out of the millions of people who ride the thousands of rides every year, there are only a small handful of incidents. You are statistically more likely to be involved in an accident driving to an amusement park than having one at a park. The rarity of accidents is one reason why the media report them, similar to plane crashes.
Every important element of a ride is inspected on a regular basis and every ride is tested every day without passengers before it opens. A ride might not open, or a safety system might activate, if there is an imperfection. For theme parks to operate, they must obtain insurance and one stipulation is their rides are frequently inspected and signed off by a strict Health & Safety governing body. Every theme park does what they can to prevent accidents because the negative press would be bad for business.
Having said all that, theme park accidents still happen…
Frisco Silver Dollar Line, Silver Dollar City, Branson, Missouri
Six guests and one employee were transported to hospital with minor injuries when the park’s stream train derailed. Source
Wacky Worm, Senor del Nicho Fair, Tlapa, Guerrero, Mexico
An approximately 30-year-old woman died after she was electrocuted by cables of the kiddie coaster, which caused her to be flung from the vehicle and hit her head on the ground. Source (in Spanish)
Treetops Rollercoaster, Oakwood Theme Park, Wales, UK
A man was airlifted to hospital after he was ejected from the Treetops Rollercoaster when the last car appeared to derail. Source
Remolino, Izamal Fair, Yucatan, Mexico
A 32-year-old man and a woman were ejected from the Himalaya/Matterhorn style ride after a screw broke from the seat lock. Both guests fell several meters to the ground and were transported to hospital with head injuries. Source (in Spanish)
Panoramabahn, Europa Park, Rust, Germany
A 3-year-old girl was airlifted to hospital after she suddenly ran onto the Panoramabahn station tracks as a train approached and grazed her. The child was in the company of her parents, which is required for anyone under 6 years of age. Source (in German).
Rebel Coaster, Royal Melbourne Show, Australia
A 26-year-old woman was transported to hospital in a critical condition suffering from injuries to her arms, legs, back, neck and face after being struck by the Zyklon/Galaxy model roller coaster. The incident occurred when she walked onto the coaster track to retrieve her mobile phone, was struck by the train and thrown several meters into the air before landing on the ground. Source
La Isla, Allou Fun Park, Attica, Greece
Four people were injured, two critically, when they were ejected from the log flume ride when a momentary drop in the water level inside the trench caused their boat to suddenly stop. Source
Drop Tower, Phase 8 Fair, Mohali, Punjab, India
At least 10 people, including five children, were critically injured after the transportable rotating drop tower came crashing 50 feet (15m) to the ground. Source
Rocket, Southport Pleasureland, Merseyside, UK
A young girl was taken to hospital with a head injury when the Pinfari Mini Mega roller coaster stopped mid-ride. Source