A mother is under arrest on suspicion of murder after her four-year-old daughter was found dead.
The 31-year-old woman walked into Manchester Royal Infirmary at around 7.15pm last night and ''expressed concerns'' about the welfare of her child to doctors and nurses.
Staff contacted police, who went to a house in Moss Side in Manchester, around two miles from the hospital.
At the address, a two-storey council house, officers made the grim discovery of the child's body.
It is understood there are no obvious signs of injury to the child and a post-mortem examination will take place to establish cause of death.
Sources said the woman under arrest is the mother of the child and had gone into the hospital and told staff her daughter was dead.
Police are not looking for anyone else in relation to the murder.
A source close to the inquiry described the incident as ''sad and tragic''.
A spokesman for Greater Manchester Police said: ''Police have launched a murder inquiry after the death of a four-year-old girl.
''At 7.15pm on Thursday September 22 2011, police were contacted by staff at the Manchester Royal Infirmary after a woman came into the hospital and expressed concerns about the welfare of a four-year-old girl.
''Officers then attended at a house on Garthorne Close in Moss Side and found a four-year-old girl deceased.
''Inquiries to establish the circumstances surrounding her death are ongoing.
''A 31-year-old woman has been arrested on suspicion of murder and remains in police custody for questioning.''
Meanwhile, a man and a woman are being questioned by police after the decomposed body of a young child was found in a house.
Officers made the grim discovery when they were called to the terrace property in Heaton, Bradford, at about 2.40pm on Wednesday.
Detailed forensic examinations are being carried out to determine the age and gender of the dead child. It is understood the child has been dead for some time.
A spokesman for West Yorkshire Police said: "Inquiries are ongoing to establish the cause of death of the child. A 40-year-old woman and a 22-year-old man have been arrested and are in custody."