Lompoc City Fire responded to a house on fire around 9 a.m. on the 600 block of University Drive.
Officials said the fire started on second floor of home. When crews arrived, part of the second floor collapsed and made it difficult to reach flames on that level.
Authorities said one firefighter suffered non-life threatening injuries.
No one was inside home at the time of the blaze. Lompoc fire investigators noted the house was recently sold. Arson Task force will be investigating the cause of the fire.