Warrnambool CFA station officer in charge Paul Marshall said about 20 litres of ammonia had leaked after a flange failed at the factory.

Mr Marshall said most of the 20 litres was contained within a bunded area with only a small volume going beyond that.

He said the incident was reported at 7.45am and was resolved by 11.45am.

Mr Marshall said three CFA units from Warrnambool at the scene were assisted by a heavy hazardous materials unit from Ballarat that provided monitoring equipment.

In other incidents in Warrnambool today, a cow had to be euthanased outside Warrnambool Primary School after escaping from a cattle truck.

Dean McKenna of Midfield Meat said it was decided it would be too stressful for the cow to try to reload it and it was euthanased on Raglan Parade under a tarpaulin away from public view.

He said it was believed the cow had escaped on the western side of Warrnambool and made its way to Warrnambool Primary School where it was captured by a Midfied Meat employee.   

EARLER: Staff have been evacuated from Fonterra following an ammonia leak at the plant earlier this morning. 

Warrnambool CFA operations officer Paul Marshall said the leak occurred at the Dennington factory about 7.50am on Wednesday. 

“A quantity of ammonia has leaked from the boiler house, which has caused the evacuation of staff from that area of the site,” he said. 

“The leak has been isolated and we are waiting for the remaining ammonia to dissipate. This will either happen naturally or we may recover it, which is safe to do so.” 

Mr Marshall said three Warrnambool appliances were on the scene. 

“There is about 20 personnel on the scene and another appliance from Ballarat on its way,” he said. 

“The cause of the leak has not been established. There have been no injuries.”