Police were called to a quiet suburban street in the western suburb of Doonside at 8.50pm on March 18 after receiving reports of a dispute.

Officers arrived to find two people, a 42-year-old woman and a 41-year-old man, seriously injured after the alleged hit and run.

The woman suffered a head injury and was in a serious but stable condition after being rushed to Westmead Hospital.

The man is fighting for his life at the same hospital after sustaining significant injuries to his head, chest and leg.

The pair was allegedly hit by an SUV, officers were told.

A 27-year-old man was arrested nearby and taken to Blacktown Hospital for "precautionary reasons" under police guard.

He was charged with five offences including using an offensive weapon with intent to commit an indictable offence, causing grievous bodily harm to person with intent, assault occasioning actual bodily harm, failling to stop and assist after vehicle impact causing grievous bodily harm and dangerous driving occasioning grievous bodily harm.

The man was refused bail to appear at Blacktown Local Court on the afternoon of March 19.