Revelers celebrate opening of running of the bulls festival in Pamplona, Spain

People gather during the launch of the 'Chupinazo' rocket, to celebrate the official opening of the 2016 San Fermin Fiestas, in Pamplona, northern Spain, Wednesday, July 6, 2016. Revelers from around the world kick off the festival with a messy party in the Pamplona town square, one day before the first of eight days of the running of the bulls. (Copyright 2016 The Associated Press.)

People celebrate during the launch of the 'Chupinazo' rocket, to celebrate the official opening of the 2016 San Fermin Fiestas, in Pamplona, northern Spain, Wednesday, July 6, 2016. Revelers from around the world kick off the festival with a messy party in the Pamplona town square, one day before the first of eight days of the running of the bulls. (Copyright 2016 The Associated Press.)

People gather for the launch of a firework rocket, known as the "Chupinazo", to celebrate the official opening of the 2016 San Fermin festival, in Pamplona, northern Spain, Wednesday, July 6, 2016. Thousands of people are singing and dancing in the streets of this northern Spanish city to celebrate the start of the Pamplona's famed San Fermin running of the bulls festival. (Copyright 2016 The Associated Press.)

People celebrate beside ''Los Gaiteros '' musicians during the launch of the 'Chupinazo' rocket, to celebrate the official opening of the 2016 San Fermin Fiestas, in Pamplona, northern Spain, Wednesday, July 6, 2016. Revelers from around the world kick off the festival with a messy party in the Pamplona town square, one day before the first of eight days of the running of the bulls. (Copyright 2016 The Associated Press.)

People are refreshed with water thrown from a balcony during the launch of the 'Chupinazo' rocket, to celebrate the official opening of the 2016 San Fermin Fiestas, in Pamplona, northern Spain, Wednesday, July 6, 2016. Revelers from around the world kick off the festival with a messy party in the Pamplona town square, one day before the first of eight days of the running of the bulls. (Copyright 2016 The Associated Press.)