Half-tonne fighting bulls gored two Spanish men on Sunday as thousands of red-scarved daredevils sprinted down narrow dew-slicked streets in Pamplona's annual running of the bulls.
One man received a 12-centimetre (five-inch) gash to his neck while the other was gored in his armpit, the local government said on its website. Both are listed in serious condition in hospital.
Another three Spanish men suffered bruises and cuts as the bulls trampled and knocked over runners during the fourth bull run of the week-long San Fermin festival, which was broadcast live on Spanish television.
The Sunday bull run is usually one of the most crowded of the festival, which was immortalised in Ernest Hemingway's 1926 novel "The Sun Also Rises".
The daily runs see people dashing with six bulls along a winding, 850-metre (more than half a mile) course through narrow streets to the city's bull ring, where the animals are killed by professional matadors in an afternoon bullfight. The festival ends on Thursday.
A total of eleven men have been gored in the four bull runs held so far this year in Pamplona, including three Americans, a Japanese national, an Indian, a Canadian and a South African. All but one of the victims of the gorings remain in hospital.
The festival, which also involves religious processions, concerts and all-night drinking, attracts thousands of visitors from around the world.
Over the past century fifteen people have died from gorings in the fiesta, which dates back to medieval times. The most recent death took place in 2009.
Bull fights and bull runs are a traditional part of summer festivals across Spain.
On Saturday, a 29-year-old Spanish matador was gored to death in the ring in the eastern town of Teruel in a bullfight that aired live on television.
He is the first matador to be killed in the ring in more than three decades.
And a 28-year-old Spaniard was killed also on Saturday during a bull run in the southeastern village of Pedreguer near Valencia.