Private security guards at the Cape Peninsula University of Technology's (CPUT) Mowbray campus released tear gas on Tuesday over apparent unrest there.
"There is some disruption in the business facility," confirmed CPUT spokesperson Lauren Kansley, adding that she had no further details at the time.
"Everyone is out of campus now. The campus is shut down," said one student.
A few minutes later, she said students were told that those who did not have classes for the rest of the day should go home. Those who did, could stay.
"I don't know what's going on anymore. They are just confusing all the students," she said.
The police were also arriving, she added.
The security guards are part of the same company from which 28 were arrested last Wednesday for allegedly not being registered in terms of the Private Security Industry Regulation Act (PSIRA Act).
Asked why they were still using the company, Kansley said: "That is their problem with their staff. The onus is on the company to ensure that their staff are appropriately registered."
Further information was not immediately available from the police, or the security company.
Earlier, there was a short-lived shutdown at a library at the University of Cape Town.
The library was reopened shortly afterwards.
Students are still a little jittery after three years in a row of protests - some violent - that saw lectures disrupted and exams delayed.