A learner driver has been charged after allegedly running over another man and fleeing the scene following a confrontation in northwest Sydney.

Police were told the 27-year-old learner driver and a 38-year-old man arrived in separate cars at a home on Faithfull St in Richmond about midnight on Wednesday.

WATCH THE VIDEO ABOVE: Man struck in alleged hit-and-run in Sydney’s north-west

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The older man allegedly falsely claimed to the residents that he was a NSW Police officer.

After speaking with the residents, he allegedly assaulted one of the occupants, a 16-year-old boy.

The 27-year-old then tried to reverse his Hyundai SUV away from the home but ran over the 38-year-old, police say, before failing to stop and driving from the scene about 12.35am.

The 38-year-old was rushed to Westmead Hospital in a critical condition. Credit: 7NEWS

The 27-year-old allegedly hit the 38-year-old before fleeing the scene. Credit: 7NEWS

The 38-year-old was treated by paramedics before being taken to Westmead Hospital in a critical condition.

Police arrested the 27-year-old a short time later on Francis St.

He allegedly returned a positive roadside breath test and was taken to Windsor Police Station.

The man was charged with 10 offences, including two dangerous driving charges, failing to stop and assist after causing grievous bodily harm, causing bodily harm by misconduct while in charge of a vehicle, negligent and reckless driving, mid-range drink-driving, driving unaccompanied as a learner and failing to display L-plates.

He was refused bail and was scheduled to appear before Penrith Local Court on Wednesday.

NSW Police told 7NEWS.com.au the pair were known to each other, and the 38-year-old could also face charges once he is deemed fit to leave hospital.

Investigations are underway.