Two teenage boys had to be rescued after a Winter Wonderland fairground ride failed.
The elastic and gearbox on one side of the Slingshot failed, with the pod holding the pair slamming into a metal support.
In a video shared on social media, the pod can be seen dangling above the ground with the two young riders still inside.
Staff can also be seen escorting spectators away from the scene.
Becky Littlewood, who took the video, described the scene as “very scary”.
She had been attending the attraction in London’s Hyde Park with her husband on Wednesday night when the accident happened.
“There were so many rides there and this particular ride had quite a few people queuing outside of it,” she told the PA news agency.
“I really wanted to go on it. But my husband looked at me and he said ‘No, you’re not going on that, it doesn’t look very safe.’
“And then, just as we were walking off, we heard this massive bang.
“The side had snapped and catapulted the people into the air, and then it hit the side of the ride.
“Obviously everyone was screaming. And then security kept trying to usher us away and telling us to put our phones away and get out of the area.
“They were sat there for about 20 minutes while they figured out how to get them down.”
Her video of the incident has since gone viral.
“I don’t know how it happened,” Ms Littlewood said. “I was in London and I uploaded the video. And then my husband said ‘Have you seen how many views it’s got?!'”
The 33-year-old, from Suffolk, said the experience would not put her off going to fairgrounds in future.
“I wouldn’t go back to this one,” Ms Littlewood added. “But I’d go to others.
“But I would avoid this sort of ride because they seem a bit unpredictable.”
London Fire Brigade and the Metropolitan Police said they were called out to the incident but the riders had been rescued by the time they got there.
The Met said in a statement: “Police were called at 20.22 on Wednesday 14 December to reports of two people trapped in a bungee ride in Hyde Park.
“Officers attended along with London Fire Brigade.
“It was reported that two teenage boys have been in a fairground ride when there was an incident that left the cage they were riding in suspended in the air.
“The cage had been lowered down before police arrived and the boys had also left the scene. There were no reported injuries.
“A preliminary inspection indicates there was a technical fault within a sealed gearbox that controls the release of the elastic cord and steel wire rope. Further inspections are ongoing.
“The Health and Safety Executive has been alerted about the incident.”
Winter Wonderland is a major London attraction featuring rides and festive market stalls. It is estimated millions of visitors attend each year.
A Winter Wonderland spokesman said: “We can confirm that a technical issue involving the reverse bungee occurred on Wednesday evening. Both riders were safely escorted off the ride, checked by our on-site medics and were not injured.
“Safety is our highest priority and the ride is closed while further investigation takes place.
“All of our rides undergo rigorous and regular safety checks by experienced members of staff trained in health and safety. We also provide regular training for all staff to ensure our visitors can enjoy a fun and safe experience.
“All other attractions at Winter Wonderland are operating as normal.”
The Amusement Device Inspection Procedures Scheme, an organisation that monitors the safety of amusement park rides, said: “We can confirm that the elastic cord and the steel wire rope supporting the reverse bungee gondola in which the public sit has not snapped or failed in any way.
“We inspected the ride at 7am this morning and it was found that a technical issue had occurred within a sealed gearbox that controls the release of the elastic cord and steel wire rope.”