In Photos: Spain's iconic Pamplona bull-running festival kicks off

The northern Spanish city of Pamplona on Thursday marked the start of its iconic nine-day Running of the Bulls festival with the ceremonial launching of a firework known as the "chupinazo". Above: Revellers dressed in red and white fill the town hall square during the 'Chupinazo' rocket at San Fermín fiestas in Pamplona.

Thousands of revellers in traditional white outfits had gathered in the main square to see the ‘chupinazo’ blast off from the city hall balcony shortly after noon. Above: Participants wave their red scarves during the "Chupinazo" (start rocket) opening ceremony.

After the highly awaited bang, the crowds cheered 'Long live St Fermin!', in reference to Pamplona's patron saint, as bands playing the traditional txistu flute and drums led them off the square in a jovial march. Above: The "Pamplonesa' municipal music band performs during the 'Chupinazo' (start rocket) opening ceremony.

Nearly everyone, including many tourists, was dressed in the traditional garb of white trousers and shirt with red sash and neckerchief as they sang and shouted.

Spectators watch from balconies and wooden barricades set up along the course. The spectacle is televised nationally. Above: Participants wave their red scarves during the "Chupinazo" (start rocket) opening ceremony.

The festival was made famous by Ernest Hemingway’s 1926 novel 'The Sun Also Rises.'

The highlight of the nine-day festival is the early morning “encierros,” or bull runs, starting on Friday, when thousands of daredevils race to avoid six bulls charging along a winding cobblestoned route to the city’s bullring.