With treacherous Santa Ana winds as their bellows , the twin wildfires raced through populated canyons , forests and brushlands on the northern fringes of the San Fernando Valley on Monday , claiming at least one life and 49 structures , and prompting authorities to suggest a hair-raising , worst-case scenario -- that one of the blazes , which began near Porter Ranch , could burn all the way to the Pacific Ocean about 15 miles away .