PAMPLONA - Several people were injured in a stampede at Spain's San Fermin bull run on Saturday, when bulls that had chased them down the cobbled streets of Pamplona were crushed against them at the narrow entrance to the bullring.

At least one person was seriously injured, local medical officials told Spanish national television, and three were being treated for injuries from falling or being trampled. Others caught in the scrum were being attended to in the bullring.

A Fuente Ymbro fighting bull falls at the entrance to the bull ring during the seventh running of the bulls of the San Fermin festival in Pamplona July 13, 2013. Several people were injured in a stampede at Spain's San Fermin bull run on Saturday, when bulls that had chased them down the cobbled streets of Pamplona were crushed against them at the narrow entrance to the bullring. [Photo/Agencies]

Health officials said four people had been taken to hospital. A spokeswoman at San Fermin's festival media office said she had no further information on those in the bullring.

On Friday three men were gored during Friday's run, including an American tourist who had his spleen removed.

In the week-long festival, bulls chase hundreds of runners through the town's narrow streets daily at 8 a.m. (0600 GMT). Saturday's run lasted 4 mins 15 seconds.

Goring happens from time to time at the hundreds of such bull-running fiestas in Spain every year but stampedes are rare.

San Fermin attracts large numbers of visitors since Ernest Hemingway made it famous with his novel "The Sun Also Rises".