Police believe man in mysterious driveway death may have been stabbed

NSW police are still hunting an offender after a man was stabbed and left to die on a Sydney driveway earlier today.

Paramedics were called to the scene in St Clair around 12.20pm (AEST) after reports a man was badly injured.

A NSW Ambulance spokesman said the man suffered severe head injuries and was unable to be revived.

Police believe the man was stabbed and a large amount of blood was found trailing between the driveway and a park behind the vacant house.

The man's age is unclear but it is believed he is in his 20's or 30's.

Emergency services were alerted to the attack after neighbours heard screaming.

“I was in my kitchen, and I heard somebody was calling, ‘help!’, “help!’,” witness Anica said.

“[I thought] somebody has killed someone,” she said.

"We are treating it as a suspicious death at this point in time, but we have no further information as to how the injuries occurred," Superintendent Greg Peters said.

Police are now investigating the events leading up to the death but believe he was stabbed.

A report is being prepared for the coroner.

Investigators are appealing for information from the public.