Pamplona Bull Run: 4 Hospitalized by 'Massive' Half-Ton Beasts (VIDEO)

The Pamplona bull run took place in Spain Sunday, and of the thousands of runners involved in the high-risk activity, four were injured, and only one of those four are still currently hospitalized.

The Pamplona bull run, which takes place during the annual San Fermin festival, involved six bulls and six steers, who can each weigh up to 1,380 pounds. Most runs from outside the city to the bull ring take between three and four minutes, with the huge beasts chasing the runners steadily.

"We did not realize how big they would be. They were massive. They once turned round and came back again. Oh my God, it was crazy, indescribable," 25-year-old Scot Ellis of London told AFP. "We are on vacation. Stupidest vacation we've ever done."

Four people were hospitalized for their injuries: 24-year-old Australian J.C. and a 44-year-old British citizen were both badly bruised; a U.S. traveler identified as C.S. had a minor injury, and a 36-year-old native of Pamplona also had a minor injury, city officials told the Associated Press.

Despite one of the bulls being turned around, the run still took place relatively quickly, with thousands of spectators cheering on the runners, who wore the traditional red and white outfits.

"It was a very fast run," Joaquin Subasti, 52, explained. He has taken part in 39 bull runs in his lifetime.

"The bull run is always dangerous. There are gorings, broken bones, falls. It is a high-risk activity," he added.

15 have died since the Pamplona bull run began keeping records in 1911. The most recent one was four years ago, when a 27-year-old Spanish runner was gored by the horns, with his neck, heart and lungs being punctured.

Last year 20,700 runners ran with the bulls during the eight runs, with 38 hospitalized.