( CNN ) -- Firefighters in Washington have contained a massive blaze that started on one house 's roof and spread to at least 15 other homes , authorities said . Stacked logs at a saw mill were also engulfed by the fire and helped fuel the flames , Yakima County Fire Chief George Spencer said late Saturday . `` We 're talking thousands and thousands of logs . It 'll take about three or four days for that to burn out , '' he said . Authorities said the fire started around 2 p.m. Saturday in the town of White Swan , located on the Yakama Indian Reservation . Investigators do not know what caused the fire , Sgt . George Town of the Yakima County Sheriff 's Office said . Firefighters have not official determined what sparked the blaze , but are considering it to be accidental , Spencer said . He said the fire may have destroyed or damaged at least 15 and as many as 20 homes . At least 60 firefighters from 12 different fire departments battled the flames for more than eight hours . Two firefighters sustained minor injuries and were treated at the scene .
NEW : Stacked logs at a saw mill were also engulfed by the fire . The fire is on the Yakama Indian Reservation . Two firefighters are injured while battling the blaze .