Firefighters battled an apartment fire in Nanakuli off Helelua Street Sunday night.

Fire officials say the damage is primarily on the exterior of the home, but the home remains uninhabitable.  Red Cross officials were called to help the family of five who HFD says were home when the fire started.  Another family in a separate unit was also displaced.

Neighboring apartments in the five-unit, two-story structure were evacuated, but their homes were unaffected.  

Investigators are trying to determine the cause.  Fire officials have confirmed that they are looking into a gas leak, but are unsure if that may be the cause.

Damage is estimated at $25,000.  No one was injured.