PAMPLONA, Spain -- Medical officials overseeing the annual Running of the bulls in Pamplona, Spain, say that five people have been injured at the traditional festival, with at least one gored by a bull's horns.

Red Cross spokesman Jose Aldaba says ambulances were taking the injured to a nearby hospital just minutes after the race in the northern Spanish city began early Saturday.

Rain before the race left the already narrow cobbled-streets more slippery than usual, and many other runners could be seen being trampled while corralling the massive animals into Pamplona's bullring, completing the 850-meter (930-yard) course in just over two minutes.

Saturday's bulls weighed between 550-630 kilos (1,100 to 1,400 pounds) each.

The nine-day San Fermin fiesta where the bulls are run was popularized by American novelist Ernest Hemingway.