Alton Towers did not call emergency services until 11 minutes after the Smiler rollercoaster crashed on Tuesday (2 June), it emerged on Thursday (4 June).
Bosses of the Staffordshire theme park were informed that the ride had crashed at 1:57pm, but ambulance crews said the first 999 call was received at 2.08pm.
A spokeswoman for the park said one of its first responders was at the scene within "a couple of minutes," adding that security staff would have alerted emergency services as soon as an assessment had been made.
Members of the West Midlands Ambulance Service arrived on the scene at 2:35pm. They called the fire service at 2:41pm.
Sixteen people were hurt, four seriously, when the carriage they were in collided with another, empty carriage.
They remained trapped 25ft (7.6m up) in the air at an angle of about 45 degrees for up to four-and-a-half hours before being rescued.
Two men aged 27 and 18 and two women aged 19 and 17 - including boyfriend and girlfriend Joe Pugh, 18, and Leah Washington, 17 - suffered leg injuries in the accident.
Twelve other occupants – six men and six women – required medical treatment for issues including neck and abdominal injuries.
Visitors at the theme park on the day of the accident claimed the £18m Smiler had broken down hours before the crash.
The £18m ($27.6m, €24.7m) Guinness World Record holder was opened in 2013 to much fanfare but has been blighted by technical problems and closure.
In a statement, Alton Towers said: "Our community of first responders, based on site at Alton Towers, are trained by West Midlands Ambulance Service and form part of our security and medical teams.
"Once the incident occurred, a member of the ride staff would have called our first responders who arrived at the scene within minutes.
"After instant assessment they call our security department who then call 999 straight away."
The park will remain closed for the third day on Friday (5 June).
A message on the website informs guests with pre-booked tickets that they can receive a refund, exchange them for a different date or use them at Warwick Castle, Thorpe Park, Chessington World of Adventures or LEGOLAND Windsor.