Spanish media said over the weekend that Pamplona police were looking for a young man who was seen trying to take a 'selfie' of himself on his phone as he ran inches in front of the bulls.
He could be fined up to 3,000 euros ($A4,349) if they find he endangered other runners.
His actions have sparked the hashtag #eltontolmovil on social media which means "the idiot with the mobile" in Spanish.
Spanish authorities are cracking down on dare devils who shoot camera footage even as they risk their lives by running with half-tonne fighting bulls at the annual San Fermin festival.
Two Australians and a Spaniard were gored in the final and longest bull run of this year's San Fermin festival as it wound up in Spain's northern city of Pamplona.
Another four people were hospitalised for other injuries picked up on Monday as runners dressed in traditional white clothing and red scarves tripped over each other and fell as they opened a path for six half-tonne fighting bulls and six steers.
A brown bull named "Olivito" that slipped and became separated from the pack turned around to face the runners and repeatedly charged one young man, lifting him in the air and pinning him against a wall.
The man managed to escape but the bull quickly caught up with him, goring him again as he tried desperately to climb a wooden fence that separates runners from spectators.
He was gored three times, in both thighs and in the buttocks, the regional government of Navarra said in a statement.
A 26-year-old Australian was also gored three times by the same bull - in the chest, left thigh and abdomen. He underwent surgery and was recovering in hospital, the statement added.
Another Australian, aged 24, was gored in the right thigh and was treated in hospital and released.
A beast that breaks out from the pack is one of the greatest dangers in the bull runs, leaving the huge animal disoriented and more likely to charge runners.
Monday's run was the longest of the eight in this year's festival.
The bulls from the Miura ranch in Seville in southern Spain took four minutes and 47 seconds to tear along a winding 800-metre course from their holding pen to Pamplona's bullring where they face matadors and death in the afternoon.
In all, 42 people have been hospitalised after taking part in the bull runs at this year's festival, including eight for gorings.
Dozens more were treated at the scene for scrapes, cuts and bruises suffered in falls.
The morning bull runs are the highlight of the nine-day festival which dates back to the Middle Ages and was immortalised in Ernest Hemingway's 1926 novel "The Sun Also Rises".
They are believed to have started when butchers began running ahead of the beasts they were bringing from the countryside to the San Fermin festival.
The festival also includes bullfights as well as concerts, nightly fireworks and religious processions. But it has become notorious for its raucous night life, with bars staying open until 7am.
Fifteen people have died in the bull runs since records started in 1911, most recently in 2009 when a 27-year-old Spanish man was gored through the neck and chest.
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