The National Transportation Safety Board (NTSB) has launched an investigation into the Aug. 10 explosion and fire at the Flower Branch Apartments in Silver Spring, Maryland.

Seven people died in the blast and 31 were injured. Some residents who fled the fire been allowed to return to the building, but news sources say they are living in fear and afraid to cook with gas stoves – because the cause of the explosion is still unknown. A number of families are seeking psychological help.

NTSB investigators from the Office of Railroad, Pipeline, and Hazardous Materials Investigations have been on scene of the accident since last Thursday, assisting the Bureau of Alcohol, Tobacco, Firearms, and Explosives and the Montgomery County, Maryland, Fire and Rescue Service in the investigation of the source of the explosion. Representatives from Washington Gas Company have helped with the evidence recovery and system testing.

NTSB Senior Pipeline Inspector Ravi Chhatre will serve as the investigator-in-charge.