The number of properties without power in Mangere East is unknown following a pursuit which culminated in the fleeing car crashing into a transformer.
A police pursuit ensued after officers stopped and attempted to approach a vehicle around 2pm but the driver fled from the scene.
However, the driver crashed into a traffic island followed by the transformer on Buckland Rd in South Auckland.
A spokesman for Vector said crews onsite were unable to start work on the damaged transformer while the serious crash unit investigates.
"As a result, we're not able to confirm the number of customers impacted," spokesman Matthew Britton said.
"Our crew will stand by until we're able to access the site again and will continue to evaluate options for redirecting the flow of power to restore some customers if possible."
Pictures from the scene of the crash show a BMW car crashed into the transformer, where it came to a stop.
The back window and rear taillight of the car were broken and the fence beside the footpath and ground ripped up.
A police spokesperson said the driver sustained serious injuries and was transported to hospital by ambulance.
The passenger of the car, which side hit the transformer, reportedly suffered minor injuries.
Cordons have been put in place between Lyncroft St and Wickham Way on Buckland Rd and police expect the road to be closed for some time.
Auckland Transport said delays should be expected when driving through the area and advised motorists to avoid the crash site if possible.
Britton urged the public to stay safe on the roads and take extra caution around any electrical equipment which had been damaged.
"Network equipment should always be treated as live, and if they see them damaged or down following incidents like this," he said.
If anyone comes across damaged power equipment they are advised to keep clear and contact Vector on 0508 VECTOR.