"An altercation has taken place and the victim has fallen to the ground. The offender has then allegedly driven off in her vehicle.
"The victim was found by a member of the public on the ground, coming in and out of consciousness."
Small said police received several calls from members of the public about the woman's car being driven erratically on the South Western motorway towards Counties Manukau.
"They reported that it was being driven the wrong way on the motorway and was driving dangerously."
He said the car was seen pulling into an address in Mangere but the alleged offender ran away.
Police carried out a number of area enquiries and found him soon after.
Small said they were not looking for anybody else in relation to the incident but are asking for the public's help.
"Police are now asking any members of the public who may have seen a 2000 blue Toyota RAV4 being driven between the hours of 1.30pm and 3pm in both the New Lynn area and on the South Western motorway. This will assist police in building a full picture of what has occurred today."
A staffer at the JB Hi-Fi store said they had noticed police in the area at the time, but did not know what had happened.
Another worker in the area, who did not want to be identified, said just before 7pm that police officers remained at the site carrying out their work.