Re Analysis of Photographs
It's notoriously difficult to determine if an explosion is internal or external based on a few photographs.
You can easily get impact damage on one part of an aircraft from an explosion on another part. Even disintegrating wheels do this.
A proper investigation - which will happen for sure - will determine the location and type of any disruptive event. For reference, look at the NTSB report on TWA-800 which spent a very long time eliminating a US Navy missile, or terrorist missile, or an internal bomb as the cause for the observed damage.