The Smiler, Alton Towers, Staffordshire, UK

Four riders were seriously injured when two of the coaster’s trains collided into each other. A 17-year-old girl had to have her leg amputated above the left knee and a 20-year-old woman had her leg amputated below the right knee. Source

The Smiler Alton Towers Accident
Rescuers free injured riders.