Nine roller-coasters have been closed across the United States and Canada as new information emerges about a man who was ejected from his seat and fell to his death at a Georgia theme park.
Warning: This story contains eyewitness accounts of the incident, which may disturb some readers.
Witnesses watched in horror as 42-year-old Hassan Jihad Ibn Kariem was ejected from his seat, appearing to hover above the car before striking several people and falling to his death at Six Flags over Georgia.
The nightmarish death prompted Six Flags to temporarily close nine similar roller-coasters across North America.
Six Flags over Georgia is just north-west of Atlanta. (AP: Mike Stewart)
Police and a state agency that oversees ride inspections are investigating, but many questions remain, including how the man fell out and whether there were problems with his restraints.
Mr Kariem, a school employee from Atlanta, was killed while riding Goliath, the park's tallest roller-coaster, which features a first hill measuring 61 metres.
"It looked like he was hovering because the car was moving underneath him," said Nick Mendenhall, who had just ridden Goliath with his son and was watching the coaster cars pass overhead.
The man fell headfirst back into the coaster, Mr Mendenhall said, before being ejected from the ride on its final turn.
"It felt like slow-motion, but it happened in an instant,"
he said.
"I was just praying in those moments. I was praying: 'God, please let him stay in that car.'"
Goliath towers above the entrance at Six Flags over Georgia just outside Atlanta, the state's capital city, with a series of hills and turns.
It does not take riders upside down.
There are no seat belts. Instead, riders are restrained with lap bars that pull down over their legs and waists.
In a theme park industry that is constantly introducing new thrills, it is far from the world's tallest, fastest or wildest coaster.
One family watched as the man flew out of the roller-coaster
Investigators and park employees told investigators that Mr Kareim was thrown from the roller-coaster, but officials have not released any other information about the people who were hurt.
Mr Kariem worked as the information technology manager at a public charter school and, before that, as a technology teacher.
Police and state officials are investigating the incident. (AP: Mike Stewart)
In a statement, the Wesley International Academy said it was devastated, and Mr Kariem's "dedication to our students, and commitment to our school community were evident in everything he did".
Summer Bates, who was at the park with her husband and three children, saw Mr Kariem fall.
"One thing I think that will stick with us is the sound of his body coming down," Ms Bates said.
Ms Bates said she and her family rode Goliath earlier in the day.
"My older two children rode on the car ahead of us," she said.
"I noticed they kept trying to push their [restraints] down tighter.
"I assured them that they were OK. But once my husband, youngest child and I loaded into our cart and headed up the incline, I quickly understood why my older two were messing with theirs.
"It just didn't feel secure and tight."
Amusement ride oversight varies by state
In the US, roller-coasters and other rides at major amusement parks such as Six Flags are not regulated by the federal government.
That responsibility falls to the states.
Georgia's Office of Insurance and Safety Fire Commissioner, which oversees annual ride inspections, is "conducting an in-depth and comprehensive review," of what happened, said Garrison Bennett, a spokesperson.
In California, the state approves new rides and ones that have been modified and either directly inspects them or relies on an annual inspection by the owner.
Florida's largest theme parks are exempt from state safety inspections, unlike smaller venues and fairs.
Instead, the largest theme parks, such as Walt Disney World and Universal, conduct their own inspections and have their own protocols.
Six Flags closes roller-coasters elsewhere
The roller-coaster closure comes a month after lawsuits alleging riders suffered serious brain injuries emerged at the X2 roller-coaster at Six Flags Magic Mountain. (AP: Jae C. Hong)
Six Flags Entertainment Corp temporarily shut down roller-coasters at six of its theme parks in the US and Canada.
The parks were already scheduled for seasonal midweek closures on Tuesday and Wednesday.
Those rides include a second coaster named Goliath at Six Flags Magic Mountain in Southern California; Raging Bull at Six Flags Great America in Illinois; Nitro at Six Flags Great Adventure in New Jersey; Fury 325 and Thunder Striker at Carowinds in North Carolina; and the rides Leviathan and Behemoth at Canada's Wonderland in Ontario, Canada.
The company did not say why those specific rides were shut down or what would be done before they reopened.
Bolliger & Mabillard, the Swiss company that manufactured the coaster and many others worldwide, said it was actively investigating and would not comment "until we have a better understanding of what happened".
"Our thoughts are with the family and those affected," a spokesperson said.
AP