A 4 hectare blaze that produced smoke so thick the road had to be closed has sparked a warning from a Ruakākā fire chief for people to be extra vigilant - even when doing normal activities.
Fire crews were called to a vegetation fire, the cause of which is unknown, on Port Marsden Highway about 2.30pm on Thursday.
Ruakākā chief fire officer Darrell Trigg said 10 fire appliances, 35 to 40 firefighters and three tankers attended the "rapidly developing" fire and two helicopters were on standby.
"It just took off. The grass is pretty short - maybe maximum of 3 inches high - but it just races across it because it's so dry.
"It was dense scrub over where it started so that was burning quite heavily and it was racing across the paddock towards Port Marsden Highway."
Trigg said crews monitored the road closely to ensure sparks didn't jump across it.
One lane was closed during the operation, and at times the entire road was closed to allow crews to access hydrants on the opposite side of the road.
"At one stage the smoke going across the road was so heavy you couldn't see through it which was really dangerous so we closed it. Otherwise someone could drift over the line and bang into someone else because you physically couldn't see through it."
Trigg said Fire and Emergency NZ was responding to all vegetation fires with more appliances than they normally would.
He said the danger of vegetation fires, especially in dry conditions, was that they started easily and moved quickly.
"People need to be extra vigilant around normal activities that we think are fine - even parking your car on the side of the road in tall grass with a hot exhaust. It's just things we all take for granted, could easily spark a fire.
"Also, just because something's green - it doesn't mean it's wet. It's still real dry,"