Alton Towers amusement park will remain closed tomorrow while an investigation into a "dreadful" accident on a rollercoaster which left four teenagers with serious injuries continues.
The accident happened at around 2pm on the Staffordshire resort's 50mph Smiler ride when two carriages crashed on a low section of the track.
Two males and two female teenagers suffered serious leg injuries in the crash, while the other 12 occupants required triage.
Nick Varney, chief executive of Merlin Entertainments, which runs the resort, said: "This has been a terrible incident and a devastating day for everyone here.
"I would like to express my sincerest regret and apology to everyone who suffered injury and distress today and to their families.
"The safety of our visitors is our primary concern. The park will remain closed until we understand better the cause of this dreadful incident.
"I would like to thank the emergency services for their swift and effective response today - they were outstanding.
"A full investigation is now under way and we will continue to work closely with the emergency services and the Health and Safety Executive."
An Alton Towers spokeswoman said that the park hopes to open again on Thursday and customers with tickets for tomorrow could seek a revalidation or a refund through the park's website.