The action was part of a University of Otago exercise designed to prepare staff and emergency services for responding to a serious emergency.
University of Otago emergency and business continuity co-ordinator Andrew Ferguson said he designed the exercise, based in and around the Dunedin School of Medicine's buildings in Great King St, to involve and challenge all emergency services.
''The scenario was based on a malicious chemical event.
''It was a staff member that took a chemical and was threatening to expose it to the air.''
The man was confronted by armed police, guns loaded with blanks, who simulated shooting him dead to protect public safety, Mr Ferguson said.
Fire and Emergency New Zealand crew then donned hazmat suits to enter the building, before St John paramedics assisted those who had been contaminated by the substance.
The exercise went ''very well'' and was challenging in terms of the communication between the various agencies involved, he said.
Among those challenges was the patchy mobile phone reception at the university's's new emergency operations centre in Castle St.
''We'll be getting a repeater put in.
''This is why we test things.''
