A father-and-son property development duo were targeted in an allegedly deliberate stabbing attack at a construction site in Sydney’s inner west on Wednesday, leaving one dead and the other critically injured.

Albert Metledge, 76, was killed while his son Antony, 33, was left with a knife sticking out of his back, after a labourer allegedly came at them on the site of a 90-unit residential development owned by the pair in St Peters.

Mr Metledge was unable to be revived at the scene, while his son, who was taken to Royal Prince Alfred Hospital in a critical condition, is now stable after undergoing surgery.

The attack on the pair was "not random", police confirmed.