PORTLAND, Ore. -- An improperly disposed cigarette caused a southwest Portland fire that killed a man earlier this week, fire officials said Friday.

Investigators said the cigarette smoldered in a mattress until flames erupted and spread to the rest of the house.

The body of Robert Reuwsaat, 28, was found inside the Beaverton-Hillsdale Highway home.

His roommate, Eric Salisbury, escaped the home and made a frantic 911 call to report the fire.

While investigating, crews found a working smoke detector in the home, but intense heat may have made it malfunction.

Officials said fires have caused three deaths in Portland this year.