One man is fighting for life in hospital and another is being questioned by West Australian police following an altercation outside a licensed venue.
Homicide detectives are appealing for witnesses to the incident, which happened in Bunbury on Saturday night.
They say two men were involved in an altercation outside the premises on Stephen Street, just after 10.30pm.
During the fight, both men fell to the ground before being separated by onlookers.
One of them, aged 43, received critical head injuries.
He was rushed to Bunbury Regional Hospital where he remains on life-support, police said.
A 29-year-old man was taken into custody and was assisting investigators with their inquiries on Sunday.
Detectives would like to speak to anyone who witnessed the incident or saw the men before they came to blows.
It is believed a number or people were outside the venue at the time.
Australian Associated Press