Has a cause been identified yet?
Local news has reported that it was likely sourced to a heater or boiler. I didn't hear or feel it, but I am quite a distance away.
My experience with these kind of accidents, is often thee boiler or heaters often have fugitive or corroisve pin hole leaks at their inlets. Add a flammable hydrocarbon, next to a device operating at 1500F? You get the picture.
I have also seen root cause of these, where an internal leak will superheat the water or process, and overpressure the vessel. Best news of all is that this happened about 6:30 p.m., meaning the process areas were likely clear of maintnenance folks, and contractors. As the company has completed head count with no injuries.