HONOLULU (KHON2) -- Honolulu Fire Department investigators have classified the fatal Jan. 6 Young Street fire as accidental due to unattended cooking. Get Hawaii's latest morning news delivered to your inbox, sign up for News 2 You HFD officials worked alongside the Bureau of Alcohol, Tabacco, Firearms and Explosives National Response Team to complete the on-scene origin and cause fire investigation. Honoring a hero: Honolulu mourns fallen firefighter Jeffrey Fiala Both departments determined the fire originated in a kitchen at the rear of the structure. No damage estimate has been released as a final investigation is still pending. The Jan. 6 fire claimed the life of 25-year-old firefighter Jeffrey Fiala, who served at the Honolulu Fire Department for a year and a half. On the outside of the Young Street home, a memorial continues to grow with many leaving photos, flowers, lei and remembrance of his love of the ocean and of life. Check out more news from around Hawaii Four other firefighters and an occupant were injured and hospitalized at the time of the incident. As of Wednesday, Jan. 15, only the occupant remains in the hospital.