A woman who witnessed a Tesla go up in flames after catching fire while on the Harbour Bridge overnight has described the heroic efforts of two onlookers who pulled the driver to safety moments before it exploded.

Fire crews were called to the scene just before 11.30pm after reports that a car - later identified by witnesses as a Tesla - had somehow caught ablaze.

Photos show the white Tesla’s front completely torched, with Northern fire communications shift manager Daniel Nicholson saying the vehicle was well-involved when firefighters arrived and the car was badly damaged as a result.

But from the wreckage emerged a story of heroism.

Speaking to the Herald, a witness, who wished to remain anonymous, said a driver was still in the car when it caught fire.

She described the moments before it caught fire and believes the outcome could have been different if the two “heroes” had not come to the driver’s rescue.

A car caught fire on Auckland's Harbour Bridge late last night. Photo / Hayden Woodward

“I saw smoke coming out of the tyres of a Tesla driving in the lane next to me and about 50m ahead of me in the tunnel.

“All the way there was an intense and annoying smell of burnt tyres on the motorway and over hundreds of meters of small debris on fire on the road.

“As I started to go over the bridge I saw the Tesla was on fire and the two cars ahead of me kept driving and overtook the Tesla on the right lane and pulled out in front of it.”

That’s when the two heroes sprung into action.

“They pulled out in front of it and run over to the car that had large flames coming out of the hood.

“They opened the door, pulled out a woman, one ran together with her to the other lane where the road works were happening and the second person came back to the car to look through the back right window to check if no one else was in there.

A car caught fire on the Auckland Harbour Bridge late last night. Photo / Hayden Woodward / Supplied

“They were about two metres away from the car when something exploded.

“I very much admire the quick thinking and self-control of these two people who knew what to do in that instance and their immense courage for going near the car on fire and helping this woman out.

“That was honestly a heroic act. The outcome might not have been the same without them.”

The Tesla was left torched and severely damaged after it caught fire on the Auckland Harbour Bridge late last night. Photo / Hayden Woodward

The witness told the Herald the driver was “very emotional, angry, upset” and shouted at police “I don’t know why my car is burnt”.

Two firefighters attended the scene.

No one was injured, Nicholson confirmed. The cause of the fire is also not yet known at this stage.

The vehicle has since been towed to a storage facility in South Auckland.