Federal investigators found a disconnected vent pipe in the Silver Spring, Maryland, apartment building that exploded last year, killing seven people and injuring dozens, a new report from the Bureau of Alcohol, Tobacco, Firearms and Explosives says.
However, the cause of the August 2016 explosion and fire remains undetermined, the report issued Tuesday said.
The ATF said natural gas built up in the basement room where the disconnected pipe was found.
The National Transportation Safety Board also is taking part in the investigation.
Copyright The Associated Press
