A Wellington High School staff member has been taken to hospital after inhaling a chemical in a science lab.

An ambulance spokesman said police, ambulance and fire engines all attended the callout this morning about 9.30am.

A female lab technician was taken to hospital in a moderate condition.

Principal Prue Kelly said the accident happened when the technician was preparing a lab for classes before school.

"She broke a container of bromine, and would have inhaled a couple of mouthfuls before she was able to step away. She got a bit of a shock I think."

No pupils were in the lab at the time of the accident.

Breathing in bromine can cause respiratory problems, irritation, dizziness and headaches. It can also cause skin irritation and burns.

LATEST: Three Fonterra workers injured in an ammonia spill at the Whareroa site have been treated by ambulance paramedics and are not believed to be seriously affected by the spill.

Roads to the site have now been reopened following the leak about 1.30pm.

Fire Service area chief Pat Fitzell said the leaked ammonia was being dispersed by the wind.

The Fire Service's specialist chemical hazard vehicle from New Plymouth was on its way to Hawera, Fitzell said.

olice and fire safety officers are investigating a fire at Mangere College in South Auckland this afternoon.

Fire Chief Bob Morrison said when they arrived they found the science lab and adjourning office well ablaze.

''It was quickly extinguished,” he said.

As a precaution fire crews involved underwent a chemical de-contamination.

He said it was too early to say whether the fire was suspicious or not.

The buildings suffered moderate damage.

The Mount Maunganui Fire Service attended a small chemical leak at Peter Baker Transport in Portside Drive this morning.

Fire Service communications shift manager Megan Ruru said the incident involved a small carton inside the building leaking hydrochloric acid and the fire service had been called at 6.16am.

She said a small carton was isolated and placed into a decontamination drum and removed from the building, which was then ventilated. The fire crew then went through a decontamination shower.

Two men injured in an explosion at Kaiwaka may have been making cannabis oil when volatile chemicals used to make the drug blew up, police say.

Fire and St John Ambulance services were called to a house at 9Marshall Rd, Kaiwaka, about 18km northwest of Wellsford, at 3.38pm last Thursday after reports of an explosion at the property.

When they arrived two men, aged 19 and 20, were found with serious burns and flown to Middlemore Hospital by the Northland Electricity rescue helicopter.

The men were understood to have burns to their faces, arms, torso and legs.