The 19-year-old was walking down Cowper Street in Coonabarabran at 6pm yesterday when he was approached by a man and two women, according to police.
Police were told a member of the group allegedly poured liquid on the man before he caught alight.
A passerby rushed to help the man and extinguish the flames.
The 19-year-old was rushed to hospital for treatment.
A short time later, police were called to the same street after reports of a public order incident.
A 45-year-old woman, a 19-year-old man, and a 17-year-old girl were arrested at a nearby property.
They were all taken to Coonabarabran Police Station.
The man was charged with affray and causing grievous bodily harm to a person with intent.
The older woman was also charged with affray.
They were refused bail to appear in court today.
The teenage girl was released pending further investigation.
