Police are investigating three assaults at a privately-run hospital caring for child mental health patients.
Two of the incidents at Ellingham Hospital at Attleborough in Norfolk relate to attacks on staff and a third involves two patients, police said.
The hospital has admitted to the Care Quality Commission (CQC) it has problems recruiting qualified staff and relies on bank and agency nurses.
Two wards are also to shut but this is not related to the attacks.
“Officers are currently investigating three separate incidents of assault at Ellingham Hospital,” police said.
“We are aware of the closure of hospital wards, however this is not directly related to these ongoing investigations.”
Allegations of physical assault were made in August and September after an unannounced CQC inspection.
Following inspections in January and June the hospital had decided to close two wards affecting eight patients.
The Cherry Oak ward and Woodlands ward, where beds were provided for young people aged four to 18, are to shut.
“Morale was lower on Cherry Oak ward where high intensity observations of patients were required and there was an increased number of incidents against staff,” the CQC report said.
Meeting reports from June noted staff on Cherry Oak ward were feeling “very beaten down”.
The CQC said the hospital had now successfully recruited healthcare workers and staff morale was improving.