Fire Services from Mataura and Edendale had been called and at least two ambulances have pulled up to a Fonterra plant in Edendale.

Fonterra are aiming to have most of the Edendale plant up and running by Saturday morning after a milk silo collapsed, a spokesman has said.

Emergency services were called to the Fonterra plant in Edendale at 1.51pm after a milk silo collapsed damaging part of the plant.

A Fonterra spokesman said the company was aiming to have most of the site up and running by Saturday morning.

Ben Agate Smoke or steam can be seen billowing from the Fonterra plant at Edendale, Southland.

In the mean time Fonterra was contacting farmers about their milk collection, the spokesman said.

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Fonterra chief operating officer of operations Robert Spurway said the silo appeared to have failed and the subsequent collapse damaged a nearby pipe bridge, creating the loud noise people heard.

RACHAEL KELLY/FAIRFAX NZ The scene of the collapse at Fonterra's Edendale plant.

While the cause of the incident is not yet known, Spurway confirmed there was no explosion.

The silo is one of about 100 silos on site, representing less than 10 per cent of Edendale's total capacity for raw milk storage, Spurway said.

"Whilst some of the damage may take several weeks to repair, the situation is under control."

A source said it happened in the D4 silo and a small part of a building has collapsed, rupturing some pipes, including a steam pipe, on the way.

The collapse also tore open a milk silo with a capacity of 250,000 litres, leaking milk across the site.

A BANG LIKE THUNDER

FAIRFAX NZ The incident at the Fonterra plant in Edendale.

Edendale Discounter store owner Tania Bal said she heard a loud bang, like thunder, and thought it may have come from her place.

But she soon realised it was coming from the factory.

Bal said she saw flames and smoke coming from a chimney at the factory, and then fire engines went past.

DAVE NICOLL/FAIRFAX NZ A cordon was in place near Fonterra's Edendale factory.

Edendale resident Ben Agate was about 200m from the plant when he heard a "screeching, grinding" sound.

As he got closer to the plant he heard sirens, he said.

"There was heaps of smoke billowing out."

An eye witness said steam appeared to be coming from part of the plant and it looked as though something had collapsed.

What appeared to be a "geyser of steam" was coming out of part of the plant, the witness said. The geyser has since died down.

MILK SPILL CONTAINED

Fire service media liaison Steve Lee, who was on site, said the collapse had damaged some "superstructure" of the plant.

The silo itself was 15 metres high and 4m wide, he said.

Nobody had been injured in the incident, and all people were accounted for.

There had been a milk spill, but it was contained, he said.

The fire service was working with police, ambulance, and Fonterra staff to make the area safe.

Normal operation of the plant had stopped, but essential Fonterra staff stayed on site to help turn off power and assist emergency services, Lee said.

There had been no fire at the site, and those responding to the incident were waiting for further information, he said.

A Fonterra spokeswoman earlier confirmed all staff were accounted for.

The fire service spokesman said Invercargill, Mataura, Gore, Wyndham, and Edendale fire brigades responded to the incident.

A St John Ambulance spokesman said there one ambulance and one first response unit attended the scene, but there appeared to be no people needing treatment.

A police spokeswoman said traffic diversions were put in place at Coalpit Rd and Homestead Rd.

An Environment Southland spokesman said staff

would check whether there were any potential spills which could contaminate waterways, however there had been no reports as such, he said.

The Edendale plant has been operating for more than 133 years and is the country's oldest manufacturing site, Fonterra's website says.