There were no reports of major injuries related to a gas pipeline explosion this week in Sissonville, W.Va. Several homes were damaged or destroyed, however.
NTSB investigator Robert Sumwalt said there were no reports of gas fumes detected before the explosion Tuesday. No alarms sounded at a control station operated by NiSource Gas Transmission and Storage, reports The Charleston (W.Va.) Gazette.
The company, in a statement, said it was working closely with investigators to determine the cause of the incident.
The NTSB investigator said it took about an hour before gas deliveries through the pipeline stopped.
The report said it took Pacific Gas and Electric Co. about 90 minutes to shut off gas through a pipeline in San Bruno, Calif. That gas explosion in 2010 left eight people dead and destroyed dozens of homes.