The Fire Service and police attended a gas leak tonight in Auckland.
A police spokeswoman said police were blocking the road on Great South Rd in Penrose, and were in attendance along with Fire Service crews.
A Fire Service spokeswoman said the gas leak was at 970 Great South Rd, at BOC Gas & Gear.
Five fire crews are at the scene, along with a Hazmat unit, a command unit and several operational support units.
A Fire Service spokesman said the gas leak is a "carbide spill".
He said carbide on its own is not dangerous, but it "reacts very violently with water" and becomes acetylene, which is very volatile.
Great South Rd was closed between Church St and Sylvia Park, and a 500m exclusion zone had been set up.
The spokesman said gas detectors were being used to ascertain the gas levels at the scene.
A BOC spokeswoman said all workers onsite have been evacuated, and the company is working with emergency services to "ensure the safety and well-being of everyone around the site".
A St John spokeswoman said they have had no reports of injuries but are on standby.
She said police had set up cordons in the area.