Question

is a result of injury on skin from hot objects,fire or fire crackers

Answer 1

The injury is by fire as it has heat as well as latent heat stored in it

Answer 2

hi friends
as we know fire is very dangerous we should not play with it
according to your question
if we touch a hot object like the fire we injury on skin because it's too hot and we can touch it.
for example, if we light a candle with lighter or match stick, by mistake our finger touch the light on a candle so our finger burn and its paining.
so answer is yes. 
we injured from a hot object like fire, or fire crackers.
thank you
 i hope this will helps you