A fire on a truck carrying gas cylinders near Nelson Airport has now been put out.
The blaze started around 6:30am on Quarantine Rd and nearby residents and workers were told by police to stay inside, especially those downwind.
A Fire Service spokesperson says the flames have since been put out, but there are still gas cylinders on board the truck.
Fire crews will remain at the scene to make sure nothing reignites.
The evacuation zone of 500m is expected to stay in place for another few hours.
The spokesperson says it is too early to say how the fire started.