Police are appealing for sightings of a silver BMW car in Papatoetoe in Auckland following an assault that has left a 56-year-old man with life-threatening injuries.

The victim and a friend were walking home from a function just before 2am and were on St George Street when they were assaulted by a man.

One victim, in his 40s, is believed to have been knocked out during the attack.

When he regained consciousness, he saw his friend lying unresponsive on the footpath.

Police said the offender got into a silver BMW that was being driven by a woman.

The 56-year-old man is in Auckland City Hospital in a serious but stable condition.

The other man was not taken to hospital.

Earlier this morning police cordoned off an area near St George Street and launched an investigation, as yet they are unsure of what led to the attack.

They are appealing to the public for sightings of the vehicle and have asked for anyone with information on the incident to come forward.