One man is dead and a search is underway for another after a stabbing in Sydney's west on Friday afternoon.

Police rushed to the home in St Clair at 4.30pm and conducted CPR on the man who was unconscious with serious injuries.

Paramedics arrived shortly after. Despite their efforts, the man died at the scene.

Police said initial inquiries suggested another man came to the property and became involved in an altercation, stabbing the victim before fleeing the scene.

Two women who were at the home at the time were not physically injured but will be assessed by paramedics.

Police are searching for the other man who they believe may still be armed.

"Information from witnesses indicate the man may be travelling on a dirt bike," police said in a statement.

The man is described as being aged in his mid-20s, of African appearance, with a solid build and black hair in short dreadlocks.

If sighted, members of the public are urged not to approach the man but to instead call triple zero immediately.

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