Otago University is all but deserted with more than two-thirds of students staying away following an shooting threat.
The threat was posted on an online bulletin board shortly before midnight on Monday and police said they were working closely with the High Tech Crime Group in Wellington, and also with the University.
The anonymous posting on the 4chan discussion group included a picture of a gun and referred to other 'massacres and shootings'.
The university said classes would run as usual and students and staff were sent an email yesterday afternoon and told to be alert, but not alarmed.
Police have a uniformed presence around the university perimeter and specialist plain clothes units have been stationed inside campus buildings.
But the campus was virtually deserted this morning with one lecture normally attended by 30 students attracting only five.
At a news conference this morning the police made it clear they would deal firmly with any copy cat threats.
Some at the university say it's business as usual; others will avoid the campus altogether.
Politics and linguistics student Josh Livingstone said yesterday that despite the police presence he was not going to feel safe on campus for a few days.
"Especially between hours, between classes, changing over, there's just so many people moving about in all different directions.
"You'd hardly know anyone else from a bar of soap, let alone whether they're suspiciously."
He said many families, including his own, have asked students to stay away from campus today.
"I know this kind of behaviour is quite common on the internet but it's just a little bit different when it's aimed at your particular university, at your particular town."
Student radio station Radio One intended to continue to broadcast from the heart of campus, and update students on any developments.
Programme manager Tom Tremeuan said they would continue to do so until told otherwise.
"Dunedin being Dunedin, it's hard to tell whether or not this is something that's just going to be a one-off joke.
"It's unlikely, but still quite worrying I guess. It's not fun, the whole process."
He said in light of recent shootings in the United States, this threat could not simply be shrugged off.
One incident in particular, the mass shooting at the Virginia Polytechnic in 2007 in which 32 students and staff were killed, was specifically mentioned in the online threat.
Dunedin mayor Dave Cull said it was no longer realistic to think this would never happen in New Zealand.
"Dunedin is not insulated from this kind of threat, whether it's real or not. It's a reality of life now - we live in a global world."
But the editor of Otago student magazine Critic, Josie Cochrane, said it was important not to blow this out of proportion.
"Myself and Radio One were extra cautious of not wanting to feed into the scare-mongering at all when we first found out about it, and we were just waiting for the police to get a response to us.
"At the end of the day, we wouldn't want to be perpetuating any kind of fear in people."
She said most people were not panicking, and realised how easy it was for anyone to post a message like this online.
"It's just kind of the nature of anonymous social media, which is kind of an issue in itself, how anonymous should you be allowed to be when stuff like that can pop up every day."
Internet NZ work program director Andrew Cushen said some people thought they were anonymous online and could say whatever they wanted without consequences - but that was not the case.
"There would be markers that would give the police some indication of who this person was." said Mr Cushen, "They're not wholly reliable, but when combined with other pieces of information, they may be able to show the identity of this particular person."