The cause of the four-alarm fire that destroyed or heavily damaged three Regency Woods apartment buildings July 19 was still officially undetermined mid-week.

However, Renton Deputy Fire Chief Erik Wallgren said Wednesday the fire originated on the southwest exterior side of the building that was destroyed.

Damage from the fire was estimated at $3 million.

Thirty-nine residents were displaced from their homes but nearly all found temporary housing immediately with friends or family.

No injuries were reported in the wind-whipped fire that was reported at 1:46 p.m.

At the peak approximately 140 fire personnel from Renton, Kent, Seattle, Bellevue and departments from as far as Snohomish and Pierce counties were on the scene. Off-duty firefighters backfilled Renton’s fire stations to ensure the entire city had fire coverage.