Thousands of daredevils have raced through Pamplona in a hair-raising running of the bulls, one day after an American and two Spaniards were gored by the beasts on the same streets.

There were no gorings on Saturday, but a crush of fallen runners blocked the entrance to the bullring, briefly stopping the bulls from entering it.

At least one person appeared to be seriously injured there, and four others were taken to hospital for cuts and bruises, said Javier Sesma, health spokesman for the province of Navarra.

The festival drew widespread attention on Friday when the American college student and two Spaniards were gored, and videos and photos of the attacks were seen around the world.