A driver lost control of her car which ploughed into a lamp post before rolling on to its roof.
Sparks flew from the base of the uprooted streetlight as it was flung across the road.
The driver of the Peugeot 309 was taken to hospital with serious injuries to her face.
Two other people were also hurt in the incident.
Police were called to Hazelwood Avenue, Eastbourne, by neighbours at 3.45am today.
Patrol cars parked at each end of the busy street, restricting access to motorists as a clean-up got under way.
Emergency electricians isolated live cables that were trailed across the road.
Fire crews helped to free the injured woman before uprighting the car.
Sub Officer Steve Wright, from Eastbourne fire station, said: "The post was completely out of the ground and lying across the road. The electricity cables were ripped out of it."
An Eastbourne police spokesman said an investigation was being carried out to establish who had been driving the car and how many passengers had been inside.
He said: "We know one person had serious facial injuries, which are not life threatening, and two other people had minor injuries, but we need to confirm if all those injured were in the car or pedestrians.
"Although the crash took place quite early this morning, we are hoping someone might be able to give us more information, as it could have resulted in far more serious injuries."
Anyone with any information is asked to call Eastbourne police on 0845 6070999.
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