A member of staff at a hospital has been injured in a stabbing.
The man was attacked at Royal Sussex County Hospital in Brighton at about 08:40 BST and the site was secured while checks were carried out.
Police and security staff said nobody else was injured and “staff and patients were safe”. There are no details of the injured man’s condition.
A 30-year-old man was arrested on suspicion of attempted murder in nearby Wilson Avenue at about 09:40 BST.
Sussex Police said the “apparently isolated and unexplained incident” was not being treated as terrorism at this stage.