A teenager remains in custody after being arrested last night at the Falmer campus of the University of Sussex.
Armed police searched an address in on-campus halls last night after receiving reports of a man making threats to kill.
Despite reports of guns, no firearms were found by police.
A 19-year-old was arrested on suspicion of making threats to kill and malicious communications.
Some students had to be evacuated from their residential building while it was searched by armed officers.
Sussex Police said: “Police were called to the University of Sussex campus in Brighton at just after 6.30pm on Tuesday 5 March, following a report of a man in possession of firearms and making threats to kill.
“Armed officers swiftly attended and a 19-year-old man was arrested on suspicion of making threats to kill and malicious communications. He remains in police custody at this time.
“An extensive search of an address was carried out and no firearms were found. As a precaution, a number of flats were evacuated to ensure the safety of students.”
Detective Sergeant Joshua Bellamy said: “Officers quickly responded to this incident and ensured the safety of students and the public immediately.
“The man was not found in possession of any firearms and enquiries are now ongoing to establish the full circumstances of the incident.
“We would like to thank students and the public for their patience and co-operation while this incident was ongoing.”