Story highlights Two women and two men are hospitalized with leg injuries, an ambulance service says

The crash took place on "The Smiler" at Alton Towers Resort in Staffordshire

(CNN) A roller coaster car collided with an empty car Tuesday at a UK theme park, leaving four people with serious injuries, officials said.

The crash took place on "The Smiler" at Alton Towers Resort in Staffordshire.

Sixteen people were on the ride, according to a statement from the park. Everyone was evacuated, and the four with serious injuries were transported to hospitals.

A statement from the West Midlands Ambulance Service said two men, aged 18 and 27, and two women, aged 17 and 19, suffered serious leg injuries. All four were flown to regional hospitals for treatment.

Twelve other people had less serious injuries, the statement said.

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