A Pamplona-style running of the bulls in a Spanish town outside the capital Sunday left 63 people injured, two of them seriously, officials said.

The pair were taken from the town of San Sebastian de los Reyes to hospitals in Madrid (search) to undergo urgent surgery, said Angel Pesquera, spokesman for the town's emergency unit. The others were treated for cuts and bruises, he said.

During the crowded run, people were momentarily trapped in a pileup at the bullring's entrance where the run ends. Some of the bulls then trampled over the mound of people to get into the ring, causing the large number of injuries.

The town holds a weeklong festival each summer in which daredevils run through the streets with bulls weighing as much as 1,300 pounds, much like the famed San Fermin (search) festival in the northern city of Pamplona in July.

The earliest records of bull runs in San Sebastian de los Reyes (search) go back to 1523, making them roughly as old as Pamplona's version, which gained worldwide fame from Ernest Hemingway's 1926 novel "The Sun Also Rises."

San Sebastian de los Reyes is about 10 miles north of the capital, Madrid.