An investigation is underway following an incident in Mitcham.
Police were called to an address on Monarch Parade in Mitcham at 4pm on Tuesday, 30 June to a report of a two people injured.
Officers and London Ambulance Service attended and a woman and a child were inside a property suffering injuries.
The woman, aged 35, has been taken to hospital where her injuries are deemed life-threatening.
The child, a four-year-old girl, was also taken to hospital however was pronounced dead shortly after. Next of kin have been informed.
A post-mortem examination will take place in due course.
Officers remain in the area and a crime scene is in place.
At this early stage, police are not looking for anyone else in connection with this incident.
No arrests; enquiries into the incident continue.