Television images showed one bull repeatedly tossing and butting one runner against the wooden barriers on the edge of the ring and then goring another in the back of the leg.
The spectacle lasted just over three minutes as hundreds of runners, mostly men, ran frantically ahead and alongside six fighting bulls as they charged through the cobblestone streets of this northern city.
Three other runners, all Spaniards, were treated for injuries sustained in falls during the run.
The run finishes at Pamplona’s bullring, where later in the day the bulls are killed by professional bullfighters.
Tens of thousands of foreign visitors come to the Pamplona festival that was made known to the English-speaking world through Ernest Hemingway’s 1926 novel “The Sun Also Rises.”
The adrenaline rush of the morning bull run is followed by partying throughout the day and night.
Eight people were gored in 2019, the last festival before a two-year hiatus because of the COVID-19 pandemic. Sixteen people have died in Pamplona’s bull runs since 1910, with the last death in 2009.