Wild footage has revealed the moment a good Samaritan tried to wrestle an erratic man to the ground before he broke the hold and allegedly coward punched a bystander.
Emergency services were called to the Nambour bus interchange on the Sunshine Coast north of Brisbane, about 3pm on Sunday afternoon after reports of two men being assaulted.
Police found Adam Morton, 39, with severe head injuries and rushed him to hospital where he remains in a critical condition.
James William, 31, lost a tooth after stepping in and trying to grapple the younger attacker to the ground.
Footage taken by a bystander shows the jujitsu trained-Mr William wrapping his body around the man before he slipped away and allegedly knocked Mr Morton unconscious.

An ju-jitsu-trained good Samaritan has recounted how he almost stopped an unprovoked attack at a bus station on Queensland’s Sunshine Coast on Sunday (pictured)
Police allege the attacker then stomped on Mr Morton’s head a number of times before fleeing the scene. He is yet to be found.
Mr William said the man was ‘going crazy’ and he felt obligated to become involved to try and protect others around him.
‘If I hadn’t known any jujitsu (a martial art based on grappling and subduing), I would have been in big trouble,’ he told 9News.
‘He targeted some poor guy, king hit him, and before I could turn around and get over there, he’s already stomped on his head, probably like 10 times.’
Senior Sergeant Craig Mansfield said police were ‘concerned’ about the condition of the attacker who appeared to be ‘under the influence of some substances’.
‘It was seemingly random attacks on these two victims and appears to have been unprovoked at this stage,’ he told reporters.
‘It was a brutal attack.’

James William was able to wrestle the man to the ground (pictured) before he slipped the hold and allegedly coward punched a man, leaving him fighting for his life in hospital

Police arrived at the Nambour bus interchange (pictured) to find two men but the alleged attacker had already fled the scene and is yet to be found
Mr Mansfield confirmed no weapons were involved in the attack but warned the public against confronting the man.
‘He has assaulted two people randomly so is potentially dangerous to approach,’ Mr Mansfield said.
The alleged attacker was described as Caucasian and wearing a grey jumper, dark shorts and thongs.
Anyone with information or footage of the fight has been urged to contact police.