Two Americans and a Spaniard have been gored during the first running of the bulls of this year’s San Fermín festival, medical officials in the northern Spanish city of Pamplona said.

A 46-year-old Spanish man was undergoing surgery on Friday for serious injuries to his head and leg after he was gored and then tossed by a bull.

Hospital officials said two men, aged 29 and 35, from the US had also been gored but their injuries – in the scrotum and abdomen respectively – were not serious.

More runners were treated at the event for bruises, a Red Cross spokesman said, after two of the animals separated from the other four in the pack on their way to the bullring.

They completed the 850-metre course in just under three minutes, an average speed for the run.

The bulls came from the Cebada Gago ranch, famed as fierce because its animals have caused more injuries in recent years. Since they debuted in Pamplona’s narrow streets in 1985, bulls from this southern Spanish breeding family have gored 53 people.