A 37-year-old man arrested after a two-month old baby was repeatedly stabbed has been detained under the Mental Health Act.
West Midlands police were called to reports of a stabbing in a house in Alfred Road, Handsworth, in Birmingham on Friday night.
The boy was taken to hospital and remains in a critical condition but is making good progress, a spokesman said.
The man, arrested on suspicion of attempted murder, is also in hospital.
In a statement police said: "The 37-year-old man arrested as part of this inquiry has now been detained under the Mental Health Act at a hospital facility.
"The two-month-old baby remains in a critical condition in hospital but is making good progress towards recovery."
Birmingham City Council has said social services had not had any contact with the baby's family prior to the incident.