Lightening flash can cause injury by all of the following, except-
Mechanism of injury in lightening burns are:-

Direct effect of high voltage current.
Heat, i.e. superheated air causing burns.
Expanded and displaced air, which acts as a blast wave.
Sledgehammer blow by compressed air pushed before the current (sledgehammer effect and blow death).
Direct effect of electric currrent
Super heated air
Expanded and repelled air
Compressed air pushed in front of the current