These are the horrifying moments after two rollercoaster carriages crashed into each other on Alton Towers’ The Smiler ride - as reports emerged that one victim may have lost a leg.
Some 16 people were injured in the crash, including two men aged 27 and 18 and two females aged 19 and 17 with serious leg injuries.
The other 12 occupants - six men and six women - required medical treatment, including a man in his 20s who suffered neck and abdominal injuries.
Emergency services working yesterday evening to free trapped passengers
Theme park guests posted bloody images of the scene on social media yesterday after two carriages crashed on a section of the 50mph ride
Alton Towers bosses have refused to put a time-frame on the theme park reopening following the incident.
Nick Varney, chief executive of Merlin Entertainments which runs the Staffordshire attraction, said a fail-safe designed to prevent the sort of accident which left four people with serious injuries yesterday "didn't work the way it used to".
Mr Varney made the decision to close the park yesterday evening, and said he was unable to comment on when it might reopen, with investigators looking at the possible cause of the incident.
He told BBC News: "At this moment in time I just thought it (closure) was the right thing to do yesterday. It was an unusual and very tragic accident.
"Today we will take ... a more measured view of what was going on and whether it was specific to just the Smiler and take a view about opening Alton Towers.
"I and the whole team are totally devastated by what happened yesterday."
He said the two carriages "should not have been on the same piece of track".
He said: "Technically that should not have happened.
"The Smiler is a relatively new ride, all rides have teething problems when they open. Guest safety on those sorts of incidents is not really a major issue in the sense that when you're on a rollercoaster car, the car can't come off the track and you are restrained in the seats.
"When you have a glitch and the ride stops, it's not really an issue of safety to the riders.
"What happened yesterday is something that there are other fail-safes for. There are other braking locks that should stop two cars being on the same track, but that didn't work the way it was supposed to."
Passengers were trapped at a sharp angle while waiting to be rescued
The four people who suffered critical injuries were airlifted to major trauma centres after the 16 occupants were rescued from 25ft up in the air at an angle of about 45 degrees.
The ordeal for some of the occupants lasted more than four hours, with the evacuation not complete until 6.35pm.
A full investigation with the involvement of the Health and Safety Executive was launched soon after.
A witness, speaking on the Today programme, said she was shocked by what she considered a slow response from Alton Towers. She claimed that no-one from the theme park appeared on the scene for 10 minutes, by which time the "blood was dripping down" from the ride carriage.
She said that saw only "one lone man" approach the Smiler ride and "ask if everyone was ok".
It was not clear where the woman was when she witnessed the crash.
A spokeswoman from Alton Towers told The Huffington Post UK that the crash took place in a low section of the ride, not near any viewing platforms where witnesses would likely have been standing.
The theme park remains closed today
The spokeswoman said that ride staff and emergency services were on the scene "immediately" but it would have taken time to access the carriages, which are difficult to reach. She said that Alton Towers has its own response team which is medically trained and would have been on the scene within "seconds or minutes". She said she was confident that the teams responded "as fast as they possibly could".
The £18 million rollercoaster, which boasts a world record 14 loops, has been closed twice because of safety concerns since opening two years ago.
In July 2013 it was closed after reports that a bolt was seen to have fallen from the ride and in November that year the rollercoaster was closed after plastic guard wheels came loose and hit front-row riders.
According to the Mirror, the ride also broke down on its preview night leaving 16 journalists stranded for around 30 minutes.
Following the accident, Merlin Entertainments was the biggest faller on the FTSE 100, with shares down 3%.
The firm, based in Poole, has run Alton Towers since buying out previous owner the Tussauds Group in May 2007.