MADRID , Spain ( CNN ) -- A Chicago man who just co-authored a book on how to run with the bulls in Pamplona was gored in the right thigh on Wednesday and underwent surgery in hospital , two friends with him in Pamplona told CNN . Bill Hillmann , 32 , was gored by a bull that got separated from the other five bulls -- toward the end of the 850 meter , or half-mile , course -- just before the downhill slope leading into the bull ring. `` 'It 's been a hell of a sh**ty fiesta so far , ' `` Hillmann said at the hospital , according to his friend Alexander Fiske-Harrison , who edited their new e-book entitled `` Fiesta , How to Survive the Bulls of Pamplona . '' Other contributors to the book include John Hemingway , grandson of Ernest Hemingway , who brought global fame to the ancient tradition through his 1920s novel , `` The Sun Also Rises , '' also published under the title , `` Fiesta . '' Hillmann has been running in Pamplona for about a decade , and in the book on surviving the running , he wrote a key chapter offering detailed advice for novices and experts alike on how to properly run with the bulls . It includes this description : `` There 's more to the ancient tradition than just surviving it . At its most pure , this is daring street-art , a dance with death and majesty , a chance to come into harmonious contact with one of nature 's fiercest monsters . '' Hillmann continued in the book : `` At its worst , it 's a bunch of panicked tourists falling all over each other in an idiotic stampede . '' And Hillmann himself said he was tripped up in the confusion on Wednesday . `` I think today was a situation where somebody pushed me and I fell over and I got gored , '' he said from the hospital in a Skype interview with CNN 's Jeanne Moos . Photographs from the scene show Hillmann on the pavement , on his back , when the bull 's horn goes into his leg . `` I did n't feel it at all . When he lifted me , that 's when I realized I was gored , '' Hillmann told CNN . `` Sadly , you know , it 's just part of the run . All the great runners have been gored . '' Fiske-Harrison said he was running on Wednesday near Hillmann and that the latter was trying to guide the loose bull -- which experts consider to be very dangerous -- toward the bull ring , when he got gored . The hospital medical report said Hillmann received two gorings , but Fiske-Harrison said there appeared to be only one main one , which he described as a `` clean wound . It did n't touch a bone or an artery . This is an honorable wound . '' He estimated it to be about a 15 to 20 centimeter gash . Hillmann 's wife went to hospital to see him and Fiske-Harrison said she was not pleased . Hillmann , who was in Spain to promote his new novel , `` The Old Neighborhood , '' about Chicago , had just days ago suffered the loss of his passport and laptop , Fiske-Harrison said . Hillmann mentioned it on his Facebook page . Hillmann remained alert at hospital , although he was sedated , and is expected to spend about four days there before he is released , Fiske-Harrison said . The six half-ton bulls from Victoriano del Rio ranch , including the one that gored Hillmann , were due to die in the bullfights on Wednesday afternoon , near where he was injured on the third day of the annual eight days of running , held at 8 a.m. local time , from July 7 to 14 . On the first four days of running this year , 20 people have been taken to hospital , five for goring-related injuries , and the rest having been hurt in falls or collisions . There have been 15 deaths among runners since records began in 1924 , most recently in 2009 when a 27-year-old Spanish man was fatally gored in the neck . Hillmann said he 'll run again next year : `` I ca n't wait to get back on the street . '' Surviving Pamplona 's running of the bulls . Opinion : 'Furious energy ' Hemingway took from the bulls .
Co-author of `` Fiesta , How to Survive the Bulls of Pamplona '' gored by bull . NEW : Bill Hilmann says someone pushed him and he fell , and was gored . Photographs from scene show Hillmann on his back , when the bull 's horn goes into his leg .