Lightening flash can cause injury by all of the following, except-
Direct effect of electric currrent
Super heated air
Expanded and repelled air
Compressed air pushed in front of the current
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).