The coaster valleyed stranding 24 passengers for five hours. The riders were given umbrellas to protect themselves from the sun. Some suffered from dehydration, but there were no major injuries. Source
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…
Star Flyer, T In The Park Festival, Balado, UK
The ride was emergency stopped by operators. The sudden stop appears to have been the source of the reported injuries and 15 people were treated on site for minor injuries. One other was transferred to hospital, but was later released. Source
Skyhawk, Cedar Point, Ohio, USA
Two riders suffered minor injuries on the screaming swing when a cable snapped and came in contact with the two park guests. Source
Inferno, Terra Mitica, Benidorm, Spain
An 18-year-old man died when he was flung from the rotating coaster seats after the restraints opened during the ride. Source
Ninja, Six Flags Magic Mountain, California, USA
Four riders were injured when a pine tree fell onto the suspended coaster’s track and caused the train to derail. Source
Opa, Mt. Olympus Water & Theme Park, Wisconsin, USA
A 63-year-old man fell from the indoor wild mouse coaster and suffered head trauma that left him in a coma at the hospital for three weeks. Poor park maintenance and employee training were cited as the contributing factors for the incident. The coaster was removed and sold shortly thereafter. Source
Bandits of Robinhood, Adlabs Imagica, India
A mother and her teenage daughter suffered serious head injuries when the coaster came to a sudden and unexpected stop. Source
The Smiler, Alton Towers, Staffordshire, UK
Four riders on the multi-looping coaster were hit by the car’s guide wheels, but no one was seriously injured. Source
Pirates of the Caribbean, Disneyland Paris, France
A 5-year-old boy was seriously injured when he was crushed by a boat after falling out of the ride. Source
Vortex, State Fair, North Carolina, USA
Five people were injured, two seriously, when a pendulum-swing thrill ride at the North Carolina State Fair jolted back to a start as riders were getting off. Source