The planned removal of dangerous chemicals from laboratories at Auckland University led to students and staff being evacuated and the substance being taken to a nearby field to be detonated.
Students and staff were evacuated from the University of Auckland's medical sciences building as emergency services worked to neutralise the explosive substance.
Fire crews moved the substance to the Auckland Domain rugby fields where Stuff understands they have dug a hole to detonate it.
People were being diverted from going through the grounds and emergency services had created a 150 metre cordon.
In a statement, an Auckland University spokesperson said that the "controlled removal and safe disposal of unwanted chemicals from laboratories in the Faculty of Medical and Health Sciences was carried out, which included a small quantity of picric acid".
"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."
The evacuation was completed around 4pm and the buildings were reopened.
Fire and Emergency services were called to the building about 1.42pm on Monday after reports of a hazardous substance on site.
"There's bottles of a substance that's hazardous with movement inside," Fire and Emergency assistant commander Dave Gatton said.
Park Rd was shut by police and FENZ to deal with the situation.
There were four fire trucks, including a hazardous materials command unit on site.
* This story was first published by Stuff.