"It was like a king-hit.
"There were no black eyes, it was just the mouth and the nose.
"He had an injury at the back of his head as well.
"He must have fallen back and smacked his head on the ground."
A deeply religious man, Moata'ane said he stood and prayed for the victim before ambulance officers transported him to Dunedin Hospital.
He later asked his children to "pray for that man" before they went to sleep.
The 25-year-old forklift driver said his wife had given birth to their fourth child on Thursday, just two days before he and his children came across the aftermath of the vicious assault.
A woman who witnessed the incident told Moata'ane one of a carload of gang members carried out the assault.
A gang member allegedly told the woman the victim had "got too lippy".
Detective Sergeant Nik Leigh, of Dunedin, said last night the 43-year-old man remained in a critical condition in Dunedin Hospital.
Police officers from the Criminal Investigation Branch (CIB) and forensic scientists from the Institute of Environmental Science and Research were at the scene yesterday.
The petrol station remained closed and cordoned off, with a scene guard stationed there overnight.
Det Sgt Leigh said police had not made any arrests in connection with the assault but were following positive leads.
"We've got some persons of interest we want to catch up with."
The CIB was yet to determine if it was "a chance encounter or something more", Det Sgt Leigh said.
Police were appealing for anyone who had information about the assault or who had been in the area on Saturday night, to contact them or provide information anonymously via the Crimestoppers line.
• Dunedin police (03) 471-4800, Crimestoppers 0800-555-111.