Firefighters returned to the scene of a Waipahu fire Thursday morning to extinguish smoldering hot spots in the walls of the one-bedroom townhouse.

The fire, which caused $40,000 worth of damage to a unit at he Royal Gardens complex Wednesday night, was “intentionally set,” a fire inspector said.

When investigators returned to the townhouse on Hanauna Street Thursday morning, they discovered hot spots, said Fire Inspector David Jenkins.

The smoke emitting from the walls of the unit was discovered at 8:51 a.m. and an engine company returned to extinguish the fire by opening the walls in the ground-floor unit, he said.

The eight-unit, two-story townhouse complex was again evacuated.

Jenkins said the original fire was reported at 10:15 p.m. Wednesday

He said the blaze was brought under control by neighbors using garden hoses when firefighters arrived at 10:21 a.m.

The townhouse sustained an estimated $25,000 damage to the structure and $15,000 its contents.

No one was home at the time of the fire and no injuries were reported.