Staff and students evacuated Auckland University's medical building on Monday after reports of a hazardous substance.
A Fire and Emergency spokesperson said they received a call about the substance at 1:42pm.
"There were four fire trucks on the scene as well as a specialist hazardous appliance truck," he said.
Staff and students were evacuated from the building using a fire alarm.
"It's the most efficient way to get people out."
Auckland University's media and communications manager Lisa Finucane told Stuff a "controlled removal and safe disposal" of unwanted laboratory chemicals, including a small quantity of picric acid, was carried out.
"Given the highly volatile nature of this substance in some states, the faculty contacted Fire and Emergency NZ for support in its removal. FENZ advised the evacuation of faculty buildings as a precaution while the substance was safely removed."
Stuff reports this was taken to Auckland Domain where it was detonated.
Two loud booms were heard in the area.
The buildings are now reopened.
