A man has been arrested on suspicion of murder after a member of staff at a hospital was stabbed to death at work.
The victim, who has not been named, was attacked at the inpatient unit of Wotton Lawn Hospital in Gloucester.
Police said the woman was taken to Gloucestershire Royal Hospital but died from her injuries an hour later.
The arrested man is aged in his 60s and is being held in custody, Gloucestershire police said.
A spokesman for 2gether NHS Foundation Trust described the situation as “tragic”.
He said: “During the incident a colleague was stabbed and after being attended by fellow clinicians, was taken to Gloucestershire Royal Hospital.
“It is with deep sadness that we confirm that our colleague died a short time later. Our thoughts remain with their family and friends at this extremely difficult time. The full facts of this sad incident are still being established and therefore it is inappropriate for us to comment further at this time.”
The spokesman was unable to confirm the role of the staff member, but it is understood the woman was not a nurse.
The 2gether website says Wotton Lawn Hospital is an 88 bed acute mental health hospital near the centre of Gloucester which provides inpatient services for the county of Gloucestershire.
The hospital has four admission wards, a nurse led psychiatric intensive care unit and a low secure unit.
It says service users are supported by a variety of healthcare workers including nurses, doctors, psychologists, art therapists, physiotherapists, occupational and sports exercise therapists.
Health Secretary Jeremy Hunt said: “The events in Gloucestershire are devastating and our thoughts are with the family, friends and colleagues of the staff member involved.”
Detective Chief Inspector Steve Porter, senior investigating officer at Gloucestershire Police, said: “Formal identification has not yet taken place. As such we are unable to release the victim’s name, photos, or tributes at this time.
“We are staying in close touch with the family, who have requested that their privacy is respected.”
Workers at Gloucestershire Royal Hospital, on the same site as Wotton Lawn, have spoken of their “shock” at the incident.
Denise Luckman, 44, an admin assistant at the endoscopy unit, said: “I’ve worked here for 10 years and nothing like this has ever happened. It has been a huge shock to everybody.
“You don’t expect to go to work, to care for patients, and to have that happen.”