Tanya Jephson was outside a school in the area this morning and told Newstalk ZB the vehicle looked like a small, late-model yellow car.
She said it had rolled almost down to the tree line between Summit Rd and Godley Head, above Evans Pass Rd and Ocean View Terrace.
Police have closed Summit Rd where it intersects with Evans Pass Rd while emergency services respond to the incident. The road will remain closed for several hours while police investigate.
Anyone currently in the Godley Head Park area will be allowed to leave through the cordon.
Summit Rd is a well-known accident area. It's been the scene of numerous crashes in the past 20 years including several fatalities.
Last year it was the site of the fiery crash that claimed the life of Tayla Alexander, 17, and later her sister Sunmara, 16.
Following the girls' deaths a petition was started calling for safety measures on the popular tourist road, including guardrails, lower speed limits and speed bumps.
As of last night, New Zealand's road toll stood at 105 dead since January, down from 156 at this time last year. Fifty-six of the 105 were driving a vehicle when they were killed, according to the NZ Transport Agency.
