Firefighters responding to a structure fire in Nanakuli Tuesday night found a portable structure completely involved in fire.

Capt. David Jenkins said the unoccupied building has not been in use for some time and may have been an old Head Start building.

The fire was first reported at 8:27 p.m. near Nanakuli Avenue and Farrington Highway.

The fire was brought under control at 8:46 p.m. and fully extinuished by 9:15 p.m.

The cause of the fire is under investigation and a damage estimate was not available.