Fire that damaged a southwest Santa Rosa home started from cigarette butts, according to a Santa Rosa Fire Department investigation.

The fire, Sunday afternoon, burned a back porch of a Trombetta Street home and caused extensive smoke damage inside.

An investigation determined the cause was butts that hadn’t been extinguished and left unattended on a plastic storage shed in the porch, Quang Pham, city fire inspector, said in an email.

The fire caused an estimated $25,000 damage and displaced three adults and three children, including owner Kristin Ramos, according to fire officials.

You can reach Staff Writer Randi Rossmann at 707‑521-5412 or randi.rossmann@pressdemocrat.com. On Twitter@rossmannreport.