Nobody was injured in the incident
Thrill-seekers at Alton Towers in England were reportedly stranded on The Smiler rollercoaster for an hour - just over a year after a crash that seriously injured five people.
In a statement the theme park said the ride was closed on Thursday morning "to investigate claims a piece of debris that had fallen from a carriage".
Guests were removed and the ride was closed for the fault to be investigated, an Alton Towers spokesperson said.
At the time of the stoppage there were 32 people on the ride, but nobody was injured in the incident.
Pictures from the scene show a carriage on its way up a vertical section of the ride's track, with people in their seats facing up.
On Twitter, Alton Towers said it was "looking to get the ride up and running as soon as possible".
In June 2015 two carriages smashed into each other on the attraction, leaving two women needing leg amputations.
Merlin Attractions Operations Ltd admitted a breach of health and safety rules over the incident.
An investigation found that the crash was caused by "human error" when a computer block was over-ridden by staff.
As a result a full carriage ploughed into the back of a stationary car on the track.