A man has been arrested over a fatal stabbing at a central Sydney unit block.

The 41-year-old was arrested at Parramatta just after 7pm on Thursday and taken to Westmead Hospital under police guard for observation.

He is yet to be charged.

Earlier on Thursday, emergency workers were called to a Pyrmont apartment complex about 8am, and found a 44-year-old man with multiple stab wounds. He died at the scene.

Police said the victim, who has been named as Bashir Zaheer, worked in the building and had been in an argument with the other man, who he knew.

A knife was also found nearby and police believe the 41-year-old fled the scene and drove away in a white car.

NSW Police Acting Superintendent Sean Heaney on Thursday said it was distressing for the members of the public who found the stab victim.

“They’re distraught as you could imagine, very, very distraught – the same as the police and other emergency services that turned up not long after,” Superintendent Heaney said.

NSW Ambulance’s Nadia Tomlinson said despite medics’ efforts, Mr Zaheer could not be saved.

“Our paramedics were tremendous in providing treatment to the man, but despite their best efforts, there was nothing more they could do,” she said on Thursday.

“The issue with treating these sorts of wounds is that you can’t always tell how much damage has actually been done internally.”

-with AAP