A digger has hit a gas main in Waimauku, North West of Kumeu, causing a leak.
Emergency services were alerted to the incident on State Highway 16, near Muriwai Rd, shortly before 9am.
The digger hit the service pipe to the Waimauku RSA, a gas company spokeswoman said.
Fire service shift manager Megan Ruru said fire crews were at the scene waiting for Vector, the area's gas company, to arrive.
She was not aware of any danger to the public caused by the leak.
Police have been notified of the incident but would only attend if fire needed assistance, a spokeswoman said.
Vector's spokeswoman said crews were on site and the gas had been shut off.
"Third party gas strikes on our network are unfortunately not uncommon, particularly in areas of construction.
"But our crew are pretty good at getting in there and sorting it out."