A murder investigation has been launched after the death of a man at a care centre for adults with mental health and drug abuse issues.
The 60-year-old died after being assaulted shortly before midnight on Monday at the Imperial Lodge care centre in Hayes, west London.
The man, who was a resident at the facility, was treated by paramedics but was pronounced dead at the scene.
A 44-year-old man, who was also a resident there, has been arrested on suspicion of murder, the Metropolitan Police said.
A spokesperson for the force said: "Police were called at approximately 11.50pm on Monday, 2 January to reports of a man assaulted at an adult care facility in Lansbury Drive, Hayes.
"Officers and London Ambulance Service attended. Despite the best efforts of the emergency services the man, aged 60, was pronounced dead at the scene.
"His next of kin have been informed and a post-mortem examination will be scheduled in due course.
"A 44-year-old man was arrested at the scene on suspicion of murder and remains in custody at a west London police station.
"Both the deceased and the man arrested were residents at the facility."
A witness said they had seen police vehicles and ambulances with flashing lights in the street outside the facility.
The witness, who did not want to be named, said: "I saw lots of police cars and ambulances, the lights were flashing but there weren't sirens."