Runners in Pamplona's San Fermín festival were sent flying into barriers and trampled by bulls during the fourth running of the famed event on July 10. The chaotic scenes unfolded as six charging 600kg bulls ran through the narrow streets, with participants attempting to stay close to the animals.

Dramatic images captured runners lying on the cobblestones, shielding themselves as the bulls thundered past. One participant was seen curled into a ball, covering his face, while another punched the air moments before the animals, and another clung to a friend's shoulder as a bull approached. Emergency teams were seen carrying an injured runner away on a stretcher.

The 'encierros', or bull runs, are a central part of the week-long festival, which attracts thousands of visitors to Pamplona each year. The bulls are released at 8 a.m. from their corral and charge to the bullring along an 850-meter route through the city's old town. Runners, known as 'mozos', try to stay as close as possible to the animals without being gored.

On the first official day of the festival, at least three people were taken to the hospital. Medics confirmed that a 61-year-old American suffered a head injury, a 20-year-old Spaniard sustained a leg injury, and a 34-year-old Spaniard had an ankle injury. A fourth person was treated at the scene, and a fifth received medical attention but did not require hospitalization. No gorings were reported on that day.

Separately, a man, believed to be around 70 years old, died of apparent natural causes late the previous night in a bar on Estafeta Street, which is part of the bull run course. His nationality was not immediately known.

The San Fermín festival, which gained international renown partly through Ernest Hemingway's 1926 novel 'The Sun Also Rises', features daily bull runs alongside parades, music, and religious ceremonies. This year marks the 100th anniversary of Hemingway's novel.

A participant runs with bulls during the fourth running of the bulls of the San Fermin festival in Pamplona, northern Spain, on July 10

Runners sprint ahead of Alvaro Nunez bulls during the Running of the Bulls at San Fermin Festival

Dramatic images show runners sprinting through the narrow streets as they are chased by six charging 600kg bulls during the fifth running of this year's festival

Another image shows a runner punching the air as he races just metres ahead of the animals' horns, while another clings to a friend's shoulder as a bull bears down behind him