A four-year-old girl has died and a 35-year-old woman is in hospital with life-threatening injuries, police said.
The pair were found with injuries inside a property in Monarch Parade in Mitcham, south London, on Tuesday afternoon.
No arrests have been made and police are not looking for anyone else in connection with the incident.
Officers and paramedics were called to the scene at around 4pm following a report of two people injured.
The four-year-old girl was taken to hospital where she was pronounced dead shortly after, while the woman's injuries are described as life-threatening.
An investigation is underway following the death of a 4-yr-old girl in #Mitcham #Merton. A 35-yr-old woman is also in a critical condition in hospital. Officers are not seeking anyone else in connection with this incident. https://t.co/7B6RSqeG1P— Metropolitan Police (@metpoliceuk) June 30, 2020
The girl's next of kin have been informed and a post-mortem tests are due to take place.
Police remain at the scene.