A terrifying and chaotic running of the bulls on Friday left a toll of 16 thrill-seekers injured and two of the eight participants gored were in critical condition, officials said.

Of the wounded, five were American citizens, three of whom suffered goring injuries, the regional government said.

One American, identified only by his initials P.G., received a 10 centimeter (4 inch) goring to an armpit, while a 46-year-old-man from Florida was gored in the right side of the groin and a bull’s horn punctured a Californian man’s calf, though his muscles were not affected.

No details were given on the condition of one American, while another was released from the hospital on the same day having sustained only minor injuries.

A 48-year-old man from Canada was one of the two people in critical condition, with severe goring injuries, including a 10 centimeter (4 inch) cut beside the rectum.

The other in critical condition was a 73-year-old man from India with several wounds to his abdomen, though none of his organs were injured, officials said.

Friday’s run was particularly dangerous as the bulls came from the breeder known for raising the animals that have injured the most runners at the Sanfermines _ an ancient feast in honor of Pamplona’s patron saint, St. Fermin.

The bulls were particularly aggressive and many separated themselves from the herd, preferring to charge at participants instead of storming through the slippery 875 meter (957 yard) course on dew-moistened cobblestones.

The fiesta in this northern city dates back to the late 16th century and also is known for its all-night street parties.

The running of the bulls was popularized among Americans by writer Ernest Hemingway, first saw the event in 1924 and immortalized it in his 1926 novel ‘The Sun Also Rises.’

Hemingway even witnessed one of the first recorded deaths at the Sanfermines, that of 22-year-old Esteban Domeno, who was gored in 1924, when he was unable to climb behind a wall to protect himself from the bull.

Each morning at 8 o’clock, six fighting bulls and six bell-tinkling steers that try to keep the beasts together gallop from stables to the town’s bullring where matadors later star in afternoon bullfights.

There have been 16 deaths in the bull runs since 1910, the last in 2009, and at least 200 serious injuries.

Pamplona, Jul 8 (EFE)