NTSB: Regulator not connected to vent led to gas leak that caused Flower Branch apartments explosion

National Transportation Safety Board officials say a mercury service regulator that was not connected to its vent line was the source of a gas leak that led to a deadly explosion and fire at a Silver Spring apartment complex three years.

The Aug. 10, 2016 explosion at the Flower Branch apartments killed seven people, including two children, and left many more injured.

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NTSB officials held a meeting on Tuesday to discuss their findings following the investigation. FOX 5's Bob Barnard was at the meeting and said the utility company was not called when residents smelled gas two weeks before the explosion.

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Barnard said NTSB officials have not revealed, and may not know, the ignition source that caused the explosion. In all, over 60 people and several firefighters were injured. The damaged building was replaced by a new building that is still under construction.