Students are being warned that pranks and "small jokes" at Otago University will be taken seriously today following an online shooting threat.
Police are urging students and staff to stay alert as the Dunedin campus opened as usual this morning.
Acting area commander Inspector Mel Aitken said at a press conference this morning the investigation into the threat was continuing.
Police had yet to identify the origin of the threat, she said.
"A number" of police staff were present on university campus, but Ms Aitken said she could not discuss the steps police were taking to address the threat.
Police warned against any pranks, including "small jokes between friends", saying they would be taken seriously.
Police were also urging people to "remain alert and vigilant" and to continue coming forward with any information about the possible origin of the threat.
The police presence on campus would continue until they felt it was no longer necessary, Ms Aitken said.
Students at Otago University hall of residence Selwyn College, one of the closest places of accommodation to the university, had not been deterred by the threat.
College warden Mike Corkery said there was a "bit of talk about it but as far as I know, no student has made the decision to not attend classes".
Mr Corkery said students were attending classes, especially as it is the last week of lectures before exams.
"It's business as usual here. That is our policy and the policy of the university," he said.
Otago University politics lecturer Bryce Edwards said it was notable that there were fewer students on campus, but the students that were present seemed "remarkably calm".
Mr Edwards had a 9am lecture and said attendance was slightly down but he was surprised students turned up.
"Students didn't seem particularly worried about the situation and like me, have noted it's been quiet and calm."
He said there were plenty of students walking around campus and there was a sense of normality.
He also noted there were police on campus but they were taking a very low-key approach.
"They [police] are wanting to foster normalcy rather than panic that might be expected."
Newstalk ZB reporter Adam Walker said there had been a "few less people this morning, but it is starting to fill out".
He said the students that he spoke to had attended their morning classes.
"I understand the lectures haven't been as full this morning," he said.
He said the university was taking a precautionary approach but it would not stop normal day-to-day business.
Several University of Otago eateries will not open today and the central library computer lab is largely empty.
Several students spoke of being on edge on campus this morning after the threat was posted by an anonymous social media user on bulletin board 4chan just before midnight on Monday.
Only a sprinkling of students was seen at the university's main computer lab this morning, just a week out from second semester exams.
In the link building, three restaurants - The Fridge, Union Buffet and Orient Express - as well as Cafe Albany, were closed for the day because of the threat, university staff said.
A student, who asked to remain anonymous, said this morning she had never seen the library so empty at exam time.
"Usually it'd be absolutely packed," she said. "You usually can't get a seat."
The student said she was "staying alert ... I'm not walking around with headphones in".
"But I wouldn't even think of staying home, because I've got three exams in nine days."
Another student, Kieran Duncan, 19, said there was "hardly anyone" in the library last night, either.
Anonymous messaging application Yik Yak, which allows users to view messages posted by the people around them, was overwhelmed by messages about the threat this morning, with several users saying they planned to skip classes today.
An Otago University Students' Association (OUSA) spokeswoman said the association was open as usual, "much like the university".
"Our advice to students is to pay close attention to any messages that come through from the university of the police," she said.
OUSA would be posting the messages on its Facebook page, and the university would also be communicating via social media and the student email network.
The spokeswoman said OUSA's student support centre on Ethel Benjamin Pl would be open as usual. "People are welcome to come in and have a chat if they're feeling stressed," she said.