A fire that caused moderate damage to a Makakilo townhouse building Thursday night was accidentally caused by soldering work on a bathroom pipe, the Fire Department said today.

Fire companies were dispatched to the two-story, four-unit building at 92-1346 Panana Street at 7:50 p.m. The fire was under control by 8:15 and declared extinguished shortly after.

No one was injured, but four families were displaced. Second-floor units were damaged by heat and smoke, first-floor units by water.

Fire investigators say the soldering of the pipe in an upstairs bathroom caused a smoldering fire in wall insulation. The fire went undetected until it produced enough smoke to activate smoke alarms.

Damage was estimated at $250,000 to all four units.