NTSB finds source of Pennsylvania chocolate factory blast

(NBC, KYMA/KECY) - The blast at a Pennsylvania chocolate factory in March was caused by natural gas. That is according to a preliminary report issued by the National Transportation Safety Board.

According to the report, a "natural gas-fueled explosion and fire" at the R.M. Palmer Chocolate Company destroyed one building and caused "significant structural damage" to an adjacent building and nearby structures.

The NTSB continues to investigate the explosion and will now focus on identifying the source of the explosion as well as reviewing collected evidence, industry practices and federal regulations.

The R.M. Palmer Company has not responded to requests for comment on the preliminary report.