Police are appealing for witnesses. Photograph: Yui Mok/PA
The medic, who was in his 60s, suffered a number of knife wounds during the incident at Southleigh community hospital, in south London. He was pronounced dead at the scene and has not yet been formally identified by police.
A 40-year-old man, who police believe was a patient at the facility, was arrested at the scene on suspicion of murder at around 2.40pm on Thursday. Police said he was being treated at another hospital in south London for an injury to his hand.
A Met police spokesman said: “We believe the man arrested was a patient residing at the facility. We retain an open mind relating to the circumstances surrounding the incident.”
Southleigh community hospital is a private medical facilityin south Croydon that provides treatment and rehabilitation for adults with long-term mental health problems.
A spokesman for the hospital said: “We are greatly saddened to confirm that a member of staff lost his life yesterday following an incident in the hospital. Our deepest sympathies are with his family, friends and colleagues. He was a valued and respected member of staff who will be deeply missed.
“We cannot say more as we are working closely with the police on their ongoing investigation into this incident.” A postmortem examination is due to take place at Croydon mortuary on Saturday.
Police said they were not looking for anyone else in connection with the killing, and they appealed for anyone with information to come forward. Any witnesses can call 101, or Crimestoppers anonymously on 0800 555111.