Emergency services were called on Tuesday (June 30) when two people were injured in their homes in Mitcham, south London.
The severity of the injuries required an air ambulance to take them to the hospital.
Police officers and London Ambulance Service attended when a woman and a child were inside a property suffering injuries.
Sadly, the four-year-old child passed away after being taken to hospital, the next of kin have been informed.
Scotland Yard has since launched an investigation into the incident.