Three people were hospitalized, including one gored, Sunday after the first day of the famed Running of the Bulls festival in Pamplona, northern Spain. His injuries required surgery, the regional government reported.
The running of the bulls in Pamplona draws about 1 million spectators every year.
Though Alvarez told the outlet he successfully ran a majority of the 913-yard course ahead of the bulls, the animals eventually caught up to him by the time he had reached the Plaza de Toros bullring.
Eight bull runs are held in the northern city every July. Video footage showed a bull approached Aaron Froelicher of Florence, Kentucky, from the back, tossed him into the air and gored him in the left thigh.
The festival, which attracts annually around a million people to the northern city, was immortalized in the 1920s by American novelist and Literature Nobel Prize victor Ernest Hemingway.
A 6-ton bull ran over and gored San Francisco resident Jaime Alvarez in the neck during the first run of this year's San Fermin festival in Pamplona, an event immortalized by writer Ernest Hemingway almost a century ago.
The pack dashed together along the cobblestoned, barricaded street course.
The person knocked in the head was taken away from the scene unconscious, but the hospital spokesman said the 25-year-old had come around in the ambulance. Toward the end, one of the bulls stumbled briefly, causing panic and at least one goring when it resumed the race and charged at some of the racers.
The race lasted 2 minutes and 23 seconds.
The annual festival also includes music performances, traditional sports and dance displays, a religious procession on Sunday to honor the local patron, a firework competition and endless partying.