Assistant Chief Scott Graham says two residents -- a male and a female -- were both seriously injured in the blast, which destroyed the home on Ashley Drive and sent debris flying 50 yards in every direction.
"The adult male remains in serious condition and the adult female remains in serious condition with life threatening injuries," he says.
After both residents were transported to a nearby burn facility, Graham says investigators spent eight hours picking through the debris to determine the cause of the explosion.
Montgomery County Fire and Rescue's fire and explosive investigation section report that the explosion was caused by an improperly installed natural gas dryer.
Graham says Washington Gas has inspected all gas feeds to the area and has determined that there is no more danger to the public. But he is reminding home owners to hire a professional to install gas appliances.
"If you're installing a natural gas appliance of any kind, someone who is licensed to install that in your jurisdiction should be installing it," Graham says.
He says residents should also contact professionals for any service or routine maintenance to their gas appliances. The explosion caused more than $700,000 in damage to the home and adjacent properties.