Two rollercoaster cars collided Tuesday on one of Britain's biggest amusement park rides, leaving four teenagers seriously injured and stranding passengers 25 feet (8 metres) in the air, officials said.
Work to evacuate the passengers was still underway three hours after the crash.
A car on the Smiler ride carrying 16 people crashed into an empty, stationary car at the Alton Towers amusement park a little after 2 pm (1300GMT), the West Midlands Ambulance Service said.
It said two teenage boys and two teenage girls suffered serious leg injuries.
The ambulance service said the four were being treated at the scene and would be transported to trauma centres by helicopter.
The other 12 people onboard were not believed to be seriously hurt.
Alton Towers, 150 miles (240 kilometres) north of London, is one of Britain's most popular tourist attractions.
