Police are carrying out an investigation after a schoolboy was found dead at a Birmingham children's home.
The body of the 15-year-old, who has not been named, was discovered in his bed at a home in Edgbaston.
A post-mortem examination and forensic tests have so far failed to find a cause for the tragedy.
A West Midlands Police spokesman said officers were called to the home by the ambulance service.
He said: "A post-mortem examination has taken place and proved inconclusive and we are awaiting a toxicology report. This is being treated as an unexplained death."
An inquest into the boy's death is due to open next week.
"Police are conducting an investigation on behalf of the Birmingham coroner in conjunction with Birmingham social services" he added.
"The youth is not being named at this stage."
City council chiefs confirmed the "tragic" death of the boy, who was in the care of Birmingham Social Care and Health.
In a statement, they said: "As in the case of all sudden deaths, we can make no further comment at this stage as the details of the case are subject to an internal investigation and a police and coroner's inquiry.
"We are deeply upset at the loss of a child in our care.
"We have expressed our deepest sympathy to the family and are providing counselling and support to the family, staff and any other young people affected."
The tragedy could put further pressure on the council's social services department, which was given a zero rating in a recent national Government audit.