Paramedics eventually arrived at the scene 22 minutes later – adding up to an agonising 38-minute wait for those hurt.
A total of 16 were injured, four seriously, when a carriage on The Smiler ploughed into a stalled cart at 50mph on Tuesday.
Video footage seen by the Mirror shows the impact came at around 1.53pm.
Alton Towers bosses say they were alerted four minutes later, at 1.57pm – but then they took an astonishing 12 minutes to call emergency services.
West Midlands Ambulance Service said the first emergency call from the Staffordshire theme park was at 2.09pm and paramedics arrived at the scene at 2.31pm.
Park spokeswoman Liz West admitted there was a delay between being alerted to the accident and calling 999.
She said the Mirror’s timing of the crash at 1.53pm “probably isn’t far off”, and said the park’s on-site medical team attended within two minutes of the alert at 1.57pm.
She added: “They assessed the situation and alerted West Midlands Ambulance Service at 2.09pm by making a 999 call.”
Peter Howell said two victims suffered open leg fractures and needed “life-saving” treatment to stop massive bleeding.
A man who was on the doomed carriage slammed the wait for help.
He said: “We were calling to staff to come and get us down but nobody came for ages. Emergency services arrived about 40 minutes later and began treating those at the front.
"It’s disgusting nobody bothered to dial 999 for 16 minutes. It was clear everybody was injured and some were in a very bad way.”
The man, who asked not to be named, told how he screamed at staff to stop the ride just seconds before the smash after spotting the empty cart ahead.
He said: “We saw the empty carriage at the bottom and we saw we weren’t going to stop. We all started shouting to the staff telling them to stop.
"I thought it was going to be the end of my life. They should tear that ride down. It's not safe.”
Today it emerged a teenager who suffered horrific leg injuries in the crash is a dancer who was taken to the theme park as a birthday treat by her new boyfriend.
Vicky Balch, 20 on Saturday, suffered heavy bleeding while boyfriend Daniel Thorpe, 27, suffered a fractured leg and punctured lung in the crash.
Daniel only recently met Vicky in his home town of Buxton, Derbys – where she is studying at the University of Derby.
Vicky was taken to Royal Stoke Hospital where her parents travelled to her bedside from their home in Leyland, Lancs.
Hotel worker Daniel underwent surgery today at University Hospital Coventry. He told relatives he thought he was a “goner” as the packed carriage hurtled towards the stranded cart.
The two and a half hours he was left dangling in the air waiting to be rescued were “the most terrifying of his life”, his grandmother Val Thorpe, 83, said.
Vicky and Daniel had been sitting alongside another couple – Joe Pugh, 18, and Leah Washington, 17 – at the front.
Joe is thought to have broken both legs and Leah also suffered horrific injuries.
Joe and Leah of Barnsley, South Yorks – at Alton Towers for their first proper date – were taken to the Royal Stoke Hospital.
The theme park remains closed today as the crash is investigated and tests are carried out on every other rollercoaster at the park.
Park owners Merlin are estimated to have racked up £1.5million in lost revenue in the three days since the crash