Four arrested after Sydney armed robbery

Three men and a woman have been arrested after an armed robbery in Sydney's west, in which the offenders allegedly used a gun and axe to threaten workers.

Police allege one of the male staff members of the Blacktown business was assaulted on Saturday morning and taken to Westmead Hospital with head and facial injuries.

Police later stopped a car containing three men aged 25, 26 and 32, and a woman, 30, on Sunnyholt Road in Blacktown.

The four have been taken to Blacktown Police Station to assist with inquiries.