Alton Towers has been temporarily closed as an investigation into the rollercoaster crash continues.
A woman aged 19, a girl aged 17, and two men, aged 18 and 27, suffered serious leg injuries on the Smiler ride on Tuesday afternoon, the BBC reported.
Twelve others required treatment after one of the carriages on the ride collided with a stationary carriage.
Two carriages on Alton Towers’ Smiler ride were involved in a collision on Tuesday afternoon, leaving four people with serious injuries.
There were 16 people in one carriage when it hit another empty and stationary carriage.
The West Midlands Ambulance Service said in a statement that it received an emergency call just after 2pm.
Community-first responders based at the theme park were first on scene, before being joined by four ambulances and an air ambulance.
The statement said ambulance staff and medics were working with staff at Alton Towers to gain access to the seriously injured passengers.
Merlin Entertainment, which runs Alton Towers, in Staffordshire, also released a statement on Tuesday afternoon, the BBC reported.
"There has been an incident on the Smiler this afternoon involving two carriages coming together on a low section of the track," the statement read. "One of the carriages was empty and the other had 16 guests in.
"The resort's fully qualified first responders were on the scene immediately to assist with the evacuation which is ongoing, and the area has been closed to allow for access to emergency services vehicles. To ensure the safe and timely evacuation of guests a platform is being constructed. This will take a few minutes but will enable us to proceed more quickly.
"There will be a full investigation once we have recovered the guests, who are our priority."
This is what it's like to ride on Smiler.
Richard James is acting head of news for BuzzFeed Australia and is based in Sydney.
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