A St John spokesman said five people suffered moderate injuries, but none required hospital treatment.
Firefighters contained the spill at about 2.30pm but a cordon around the area was still in place at 3pm.
"We currently have 25 personnel in attendance, who are working to clean up the remainder of the spill.
"They are doing this by applying a neutralising agent. We are expecting to be there for the rest of the day," the Fenz spokesman said.
Nitric acid is a corrosive acid capable of causing severe chemical burns.
If inhaled, health risks include corrosion of mucous membranes, delayed pulmonary oedema, and even death.
A Fenz spokesman said motorists should avoid the area and police are assisting with traffic control.
The premises is believed to be the Owens Transport yard but branch manager Nick Max declined to comment when contacted by the Herald.
Save