This video shows a propane tank exploding and explains what is happening.
BLEVE (Boiling Liquid Expanding Vapor Explosion) Demonstration – How it Happens Training Video. (2:23) https://www.youtube.com/watch?v=UM0jtD_OWLU
As part of your risk management plan, have you analyzed where your propane tanks are located? Do they need to be moved either now, or during emergency conditions?
Reference. Propane tanks are included in a risk management tool in the book, Outdoor Site and Facility Management: Tools for Creating Memorable Places.