Thirteen people were injured, two seriously, after the entire wheel with 10 two-person gondolas of the Paratrooper ride broke away from the main hub when the center shaft snapped in two. Source (in Spanish)
Accidents
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…
Wacky Worm, Funfair, Kırşehir, Turkey
A 43-year-man was killed and three youths were injured when the train derailed and fell over 16 feet (5m) to the ground with eight on board. The overturned train landed on top of the man, who was watching his son ride the kiddie coaster. Source
TNT Tren de la Mina, Parque de Atracciones, Madrid, Spain
At least 26 people, including six children under the age of ten, were injured when two coaster trains collided. One train appeared to be stuck and workers were trying to push it forward when the other train crashed into it. Riders were not able to brace for impact because they were wearing virtual reality headsets. Source
Sky Ride, Great Escape, Queensbury, New York, USA
A 14-year-old girl slipped out and dangled from the Sky Ride before falling 25 feet (7.6m) into the arms of guests who had gathered below. No serious injuries were reported. Source
Tagada, Poulton Gala Funfair, Blackpool, England, UK
A 12-year-old boy fractured his skull after being hurled into the gate of a Tagada fairground ride. Source
Zipper, Montoya Aguilar Fair, La Ceiba, Honduras
A 15 year old boy died when the cage door of the Zipper ride opened and he was flung through the air into the ground. Source (in Spanish)
Towne West Carnival, Wichita, Kansas, USA
A 15-month-old girl died after grabbing hold of inflatable ride aluminum fence that was charged with 290 volts of electricity. Source
Splash Canyon, Drayton Manor, Staffordshire, England, UK
An 11-year-old girl stood up and fell from the river rapids ride during a school fiend trip. The pupil was rescued from the water and air lifted to hospital, but pronounced dead a short time later. Source
Kráter, Parque Del Café, Montenegro, Colombia
A disabled 36-year-old man fell 32 feet (10m) from the Gerstlauer Euro-Fighter roller coaster and was transported to hospital with serious injuries. The double amputee was allowed to ride even though he had no legs and the coaster is outfitted with only lap bar restraints. Source (in Spanish)
Winjas, Phantasialand, Brühl, North Rhine-Westphalia, Germany
A 58-year-old park technician was pinned between two of the spinning coaster cars during routine inspection and succumbed to head injuries. Source (in German)