Several of the bulls bumped into runners and trampled on others as they raced along the narrow street course to the bull ring.
Some 1,000 people took part in the 8 AM (1130 IST) run today, which lasted just over two minutes.
The Navarra regional government said five Spaniards were hospitalized for but none for gorings. Medical officials had initially reported four injured.
The nine-day fiesta, which ends Thursday, became world famous with Ernest Hemingway's 1926 novel "The Sun Also Rises" and attracts thousands of foreign tourists.
The bulls then face matadors and almost certain death in afternoon bullfights.
Bull runs are a traditional part of summer festivals across Spain.
Eleven people, including three Americans, have been gored since the runs started Thursday.
In all, 15 people have died from gorings at the festival since record-keeping began in 1924.
