Fire officials say the cause of a house fire that seriously injured a woman Tuesday has been determined to be charcoal briquettes that were used to heat the home. Fire crews were called to a home in the 1300 block of 12th Street just after 5:00 p.m. Tuesday. When they arrived, the home was engulfed by flame. Brian O’Keefe with the Des Moines Fire Department says firefighters were able to get inside and rescue a woman from a back bedroom on the second floor. They used a back window to get the woman out of the home.