Hill End Hospital Adolescent Unit abuse probe begins
Police have received reports of physical and sexual abuse of child patients at a mental health unit.
The abuse allegedly took place at the Hill End Hospital Adolescent Unit in St Albans between 1969 and 1995, Hertfordshire Police said.
At this stage the number of victims involved in Operation Meadow is unclear, the force added.
Hill End Hospital no longer exists and a housing estate was built on the site in Hertfordshire.
Hertfordshire Police said it was continually reviewing crimes and had become aware that there may be other people who were patients at the adolescent unit who may want to come forward.
Assistant Chief Constable Bill Jephson said the force "takes all reports of child abuse seriously, no matter how long ago the offence may have occurred".
"We have officers who are specially trained to deal with these type of crimes while supporting victims in a sensitive, empathetic and caring manner," he added.
"Those who believe they have been a victim of this type of abuse are encouraged to make contact with police."
Hill End Hospital, on the outskirts of St Albans, operated from 1899 to 1995, caring for people with mental health problems.