Madrid ( CNN ) -- The first day of the annual running of the bulls in Pamplona on Thursday was a swift race through old town for hundreds of runners trying to stay a step ahead of the raging bulls , but just four runners went to the hospital with injuries , officials said . Commentators on Spanish state television TVE considered it a relatively safe start to the dangerous annual tradition in Pamplona , which has tallied thousands of injuries and 15 deaths since record-keeping began in 1924 , including the fatal goring of a Spanish man in 2009 . The run in Pamplona started 400 years ago and became popular worldwide after author Ernest Hemingway wrote about it in the 1920s in his book `` The Sun Also Rises , '' also published under the title `` Fiesta . '' It is now broadcast live across Spain by state television TVE , which pays Pamplona for exclusive rights , and positions some 20 cameras along the course . A Red Cross official at the scene initially said just one runner went to the hospital , but the Navarra regional government issued a medical report later showing that four male runners were taken to hospitals . The most seriously injured was a 40-year-old Spanish man who suffered broken ribs and a fractured shoulder blade and remained hospitalized later Thursday . The other three were released from the hospital hours after arriving . They included two Spaniards , one with bruised ribs and the other with an eye injury , and a Panamanian man , 35 , with a nose injury . Television images showed numerous runners falling hard to the pavement and the bulls trying to step over them . Most of the runners were men , mainly dressed in the traditional white outfits with red handkerchiefs , but there was also a small number of women . The six bulls were from the Torrestrella breeding ranch and weigh between 470 kgs to 635 kgs ( about 1,034 pounds to 1,397 pounds ) . Accompanied by a pack of tame steers , they exited the corral just 10 seconds after the opening rocket was fired to signal the start of the run . They moved quickly along the 825-meter ( 902 yard ) course , and it took two minutes and 30 seconds until the bulls reached the corrals of the bull ring . The bulls face certain death against matadors in a bullfight later in the day . Pamplona 's new mayor , Enrique Maya , told TVE just before the race that he had never run . He said he watched it from one of the numerous balconies along the course , which are filled with local residents or visitors , the latter typically paying top dollar for a safe vantage point . The daily run continues for eight days , through July 14 , at 8 a.m. ( 2 a.m . ET ) . It is the highlight of the San Fermin festival in Pamplona that attracts hundreds of thousands to the nonstop fiesta .
NEW : Many runners go to the hospital with injuries . Numerous people fall hard as the bulls try to step over them . Hundreds of thousands gather at nonstop festival in Pamplona .