Thrill-seekers have been left stuck on a rollercoaster at Alton Towers which previously crashed, seriously injuring five people.
The theme park visitors were on the Smiler when there was a "temporary stoppage" but nobody was injured, a spokeswoman said.
The £18 million ride at the Staffordshire attraction smashed into another carriage on June 2 2015.
Five people were seriously injured in the incident and an investigation found that a computer block stopping the ride because of a stationary car on the track had been over-ridden by staff, causing the crash.
As a result, the full carriage ploughed into the rear of the empty car, leaving two women needing leg amputations.
Merlin Attractions Operations Ltd admitted a breach of health and safety rules over the incident.
An Alton Towers spokeswoman said: "On Thursday September 1, Alton Towers Resort stopped The Smiler to investigate claims a piece of debris that had fallen from a carriage.
"At no time were guests on the ride at any risk and all were safely removed from the ride promptly by staff in line with our comprehensive standard procedures.
"As the health and safety of our guests is our priority, the ride will remain closed whilst the Resort's technical team investigate the matter."
The theme park said there were 32 people on the ride when the incident happened.
Images on social media appear to show the ride in a stationary position on its way up what looks like a vertical track, with people in their seats facing up towards the sky.
Liam Dennett, 33, from Cheltenham, was in the queue for the ride when an announcement was made about a "technical fault".
He posted videos on Facebook showing the people stuck on the rollercoaster.
Mr Dennett told the Press Association: "The ride's still closed now. We can see it in the distance that it's still closed. I would say between 30 and probably 35/40 minutes that they were stuck for."
He said he would not go on the ride after seeing what happened.
"My son still wants to go on it, but I wouldn't go on it personally now," he said.
In response to someone asking if the Smiler will be open today, Alton Towers Resort said on Twitter: "Hi ,We are looking to get the Smiler up as soon as possible, keep an eye on the queue time boards around the resort for more.