A scrub fire closed roads next to the Northwestern Motorway in central Auckland on Thursday morning and sent thick smoke around the city.
The fire closed the Newton Road overbridge in central Auckland overnight, with structural engineers called in to inspect the damage.
A thick blanket of smoke filled Newton Gully around midnight, with eight fire crews responding to the blaze.
Firefighters worked both above and below the bridge to fight the blaze, which was spreading in the bush and in the structure itself.
Assistant Commander Barry Fox told AM Fire and Emergency received "a lot of calls" due to the amount of smoke.
"The fire was well established in that area of bush and we had fire transfer up into the service ducks that fed under the Newton Road overbridge," he said.
"So it's been quite a challenging fire, we've had a large amount of smoke that's filled the Newton gully area and surrounding areas. We've received multiple calls."
The road was closed for several hours but has since re-opened.
Police told Newshub the cause of the blaze is still under investigation and all roads are open.