About 5pm a man, understood to be a patched gang member, went to a Bright St property to confront the occupant.
The occupant then challenged the man to a fight, which then spilled on to the footpath.
A patrol car was only 200m away at the time and police were "there within seconds," Senior Sergeant Mark Kirkwood said.
Two minutes after that call, emergency services were alerted to a medical event around the corner in Hall St.
A man was taken to hospital.
Meanwhile, one of those brawling in Bright St was found to have a warrant out for his arrest and so police took the 24-year-old into custody, charging him with injuring with intent and assaulting police.
He appeared in court this morning and bail was opposed.
His opponent, the gang member, came off second best and was picked up by a friend and driven to a property in Kerr Avenue, where his condition deteriorated.
The man became unresponsive and an ambulance transported him to hospital, where he remained today.
Fire crews from Cobden and Greymouth attended both incidents, as well as St John.
A Fire and Emergency NZ spokesman said the rapidity of the various developments had confused services.
Snr Sgt Kirkwood said the fact there were plenty of police on hand and two jobs had happened very near to each other would have had the neighbourhood worried.
"However, there is nothing for members of the public to be concerned about," he said.
- By Meg Fulford
