It's case closed for the Ashley Greene condo fire ... TMZ has learned, the devastating flames that ripped through the actress' L.A. apartment Friday have officially been ruled an accident.
Law enforcement sources tell us, the L.A. County Sheriff's Department, the L.A. Fire Department and the insurance company -- all of which opened an arson investigation -- are in lockstep ... the fire occurred as the result of carelessness.
TMZ broke the story ... the fire started when an unattended candle accidentally lit Ashley's living room couch ablaze.
Building sources tell us, at least four neighboring units were significantly damaged from the blaze. Insurance agents are expected to stop by today to start the claims process.
As we previously reported, Greene, her boyfriend and brother were all sleeping in the condo when the fire erupted. One of Ashley's two dogs perished.