WEST READING, Pa. (WHTM) — The National Transportation Safety Board has released a preliminary report regarding the chocolate factory explosion that occurred in West Reading in March.

The board’s preliminary reports say that natural gas fueled the explosion and fire. Investigators suspected this from the beginning of their investigation in March.

The report also says that in interviews that were conducted after the accident, investigators learned that employees from Building 2 recalled that they were sanitizing equipment in the building when they detected an odor of natural gas.

The employees in Building 1 recalled the smell of rotten eggs around the same time, according to the report.

Seven people died in the explosion, including an Ephrata woman. Eleven others were injured.

You can read the full report from the NTSB by clicking here.

In a statement, R.M Palmer has said the following:

The RM Palmer Company is aware of the NTSB preliminary report titled ‘UGI Corporation Natural Gas-Fueled Explosion and Fire,’ which was released today.  Shortly after the explosion, the NTSB asked RM Palmer and natural gas provider UGI Utilities, Inc. to assist as ‘parties’ to this federal investigation.  Because we have been asked to assist in this federal investigation, under applicable federal regulations, we are precluded from commenting on anything related to the ongoing investigation, including any information included in the preliminary report released today or any allegations that may be made in litigation relating to the incident.  Our employees’ safety and health has always been, and will continue to be, of paramount importance and we extend our heartfelt condolences to those who were impacted by this tragedy.

R.M. Palmer

Employees said they told management at R.M. Palmer that they smelled gas half an hour before the explosion, but there was no evacuation.