MCCULLY, Hawaii (KHON2) -- Federal investigators landed in Honolulu to assist the Honolulu Fire Department in its investigation into the house fire that killed one of their own. Officials said they're here for as long as it takes and will do whatever it takes to get answers. Get Hawaii's latest morning news delivered to your inbox, sign up for News 2 You On the outside of the house, neighbors continue paying their respects to firefighter Jeff Fiala, the 25-year-old who lost his life in the Jan. 6 McCully fire. "Just feeling sorry for our first responders that you know passed away right, put their lives on the line for us and everything," said neighbor Kirk Tone. Preliminary report released for fatal Kamaka Air crash Firefighters are working to keep the structure safe inside the house while investigators begin piecing together what happened. HFD took the lead in the investigation while about two dozen members of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) "National Response Team" helped assist. "We're going to do everything we can, we're going to investigate everything we can to make sure the Honolulu Fire Department and the people of Honolulu have answers as to what happened, why a firefighter was lost," said Jason Chudy, ATF officer. ATF brought certified fire investigators, mechanical engineers and special agents who are interviewing neighbors, even an accelerant detection canine. Officials are looking into every possibility. Based on the size of the house, ATF estimates its crew will be in Hawaii for about a week, but will be here for as long as HFD needs to get answers. "We want to make sure that the reason for [this firefighter's] death is thoroughly investigated and we're able to provide hopefully some closure to the ohana of the Honolulu Fire Department as well as the people of Honolulu," Chudy added. Check out more news from around Hawaii ATF said it will gather its findings and present them to HPD for their use, which could take about a month.