Four people, including an Australian, a Briton and a woman from the United States, were injured in the first running of the bulls at the San Fermin festival in the northern Spanish city of Pamplona, hospital officials said Sunday.

The run, which featured bulls from the Alcurrucen estate in central Spain, started at 8:00 a.m. with the firing of the traditional "chupinazo" rocket.

The bulls needed more than four minutes to cover the 850-meter (approximately half-mile) distance from the Santo Domingo stockyard to the bullring because one of the animals fell behind at the entrance to the plaza, posing a danger to the runners.

The old section of Pamplona was packed with people taking part in the first weekend of the festival, which started on Saturday and runs until July 14.

Four people were gored at the 2012 San Fermin festival, while 41 were transported to hospitals and 388 others were treated at the scene by paramedics for a variety of injuries.

More than 4,000 runners turned out some days at last year's festival.

A total of 150 paramedics and doctors, as well as hundreds of other personnel, are working each day to ensure that the runs take place as safely as possible.

The firing of the rocket on Saturday marked the start of nine days of revelry on the streets of Pamplona, a normally quiet town that receives hundreds of thousands of Spanish and international visitors annually during the event.

The tense and adrenaline-fueled runs are dangerous because some people take part in them after all-night drinking binges, which make them reckless and more likely to get too close to animals that weigh in excess of 500 kilos (1,100 pounds).

Hundreds of other events also have been scheduled for this edition of the festival.

The festival, begun about 400 years ago, was popularized by Ernest Hemingway in his 1926 novel "The Sun Also Rises." EFE