Underground Power Cable Cut By Bucket Of An Small Excavator
It's likely that at some point during the cut, one of the phases was shorted to the neutral;  when that happens, the line to neutral voltage in the house will be 240V rather than the usual 120V, which is enough to do some damage.  

It is not likely that shorting neutral to ground would cause any trouble at all.  The neutral is bonded to ground both at your service and at the pole - that's normal.