Alton Towers has been forced to shut down its new multi-million pound rollercoaster after reports that a bolt was seen to have fallen from the ride.
Visitors queuing for the £18m Smiler ride, which has 14 loops and reaches speeds of up to 53mph, claim they saw a piece of metal break away from the ride and land near them, leaving a gap in the track on Sunday.
Some 48 people had to be rescued from the ride, which was then closed to allow for technical teams to investigate.
Fiona Gilbert, 20, from Wolverhampton told the Express and Star newspaper yesterday: "We were stood there when all of a sudden we heard a massive clanging sound.
"We turned around and there was a metal bar not even a metre away on the floor behind us. It was just under 1ft long and about two inches thick."
The theme park in Derbyshire today confirmed it had closed the ride, which opened in May, while their technical team investigate.
A spokeswoman for Alton Towers said: "On Sunday 21st July, in line with our standard procedures, Alton Towers Resort closed The Smiler to investigate a small piece of debris that had allegedly fallen from the track.
"At no time was any visitor at any risk, and 48 guests on the ride at the time were safely disembarked. As the health and safety of our guests is our primary concern, the ride will remain closed whilst the Resort's technical team investigate."