A 76-year-old man is dead and a 33-year-old man fighting for life after a construction site stabbing in Sydney's inner west, with police now hunting for the alleged assailant.
Police on Wednesday afternoon said they were searching for a 49-year-old construction worker who fled the scene of the St Peters stabbing.
Inspector Chad Deegenaars says the three men knew each other and were linked to the construction site.
It's been reported the two victims were property developer Albert Metledge and his son Antony.
"Our investigators are finding out what the disagreement was. What the motive was, we don't know," Inspector Deegenaars told reporters on Wednesday.
"It doesn't appear to be a random attack."
Emergency services were called to the construction site on the Princes Highway about 1pm.
The 76-year-old had already died while the 33-year-old was taken to Royal Prince Alfred Hospital in a critical condition.
A manhunt is under way for the alleged attacker, who is described as being Caucasian, 180 centimetres tall and with a shaved head.
He was wearing a blue t-shirt, blue cargo-type pants and work boots, and is believed to have hitched a ride from the site to Rockdale, Insp Deegenaars said.
Police, who have obtained the weapon used in the stabbing, have warned the public not to approach the man if they see him but to instead call triple zero.
"We believe he is capable of a violent act," the inspector said.
Sydneysiders were urged to stay away from the intersection of Short Street and the Princes Highway.
Video from the scene, posted to Twitter, shows a number of men in hi-vis clothing standing in an area roped off by crime-scene tape.
A picture, posted to messaging app Snapchat, claims to show one of the stabbed men lying on his side at the construction site as his co-workers administer first aid.