The Marines were training in an amphibious vehicle when it caught fire Wednesday morning. The Marine Corps said the cause was under investigation.
The agency said Pfizer ignored hundreds of complaints that the device failed to operate in life-threatening emergencies, including incidents when patients died
The F.B.I., which is leading the investigation, said that it had not yet determined whether the blast was an act of terrorism.
Supply disruptions and environmental damage raise questions about the concentration of refineries and chemical plants along the exposed Gulf Coast.
The blast at Minnehaha Academy, which happened after builders frantically warned of a gas leak, killed a receptionist and a part-time janitor.