Maybe he just had it loose in the bag (pistol), something got through the trigger guard and recoil caused more than one shot... I heard about an LEO type that hung their weapon by the trigger guard on the bathroom stall hook, apparently it was pretty exciting as the gun spun firing until the mag emptied
Why a gun should never just be tossed in a purse or tote without being in a pocket holster! Better yet, being in a holster in a "gun only" pocket of the purse/tote.