Two people have been arrested in England on suspicion of murdering a baby girl.
Police were called to Narbeth Drive in Aylesbury, Buckinghamshire, to reports the six-month-old had been taken ill.
Paramedics attended the property at around 4.30pm on Sunday but the baby, who has not been named, died at the scene.
A post-mortem proved inconclusive but Thames Valley Police launched a murder investigation into the "isolated" incident. The girl's next of kin have been told.
A 31-year-old woman and a 33-year-old man, both from Aylesbury, were arrested on Wednesday night on suspicion of murdering the baby.
Police have not confirmed what link the pair had with the girl. The suspects are in police custody, a force spokesman said.
Detective Chief Inspector Mike Lynch said: "We believe this to be an isolated incident and we are conducting a full investigation to establish the circumstances surrounding the death.
"A scene watch remains in place in Narbeth Drive and officers are in the area today conducting inquiries."