Fireworks kicked off Spain's annual San Fermin running of the bulls festival on Friday, with more than a million people expected, including those who will take their chances in the bull run.
The nine-day festival includes concerts and balls -- not to mention copious amounts of drinking -- in Pamplona in northeastern Spain.
But it is known to many worldwide for the "encierro", when bulls are released onto the streets each morning and hundreds of people are chased along an 825-metre (yard) course leading to the arenas where bullfights are later staged.
Runners are sometimes caught and either gored or trampled by the running bulls. Fourteen people have been killed in the event since 1911.
On Thursday, hundreds of animal rights activists took part in a "Running of the Nudes" to protest the bull run.
The demonstrators ran stripped to their underwear and sporting plastic horns, as well as the traditional red bandana worn by those who take part in the famous Spanish event.
The running of the bulls was immortalised in Ernest Hemingway's 1926 novel "The Sun Also Rises".