Firefighters responded to an incident near Banstead, where a part of a tree collapsed trapping a child.
Assistant Commissioner Pat Goulbourne said: "Earlier today firefighters were mobilised to an incident near Banstead, following reports of a child being trapped by part of a fallen tree.
"At 1601, crews from Croydon and Wallington fire stations, and a fire engine from Surrey Fire and Rescue Service’s Banstead Fire Station, were sent to the scene as part of our response.
"Upon arrival firefighters immediately began to coordinate the rescue operation, working to make the scene safe and carrying out immediate emergency care in support of paramedics from the London Ambulance Service. Sadly, despite the effort of emergency service personnel in attendance, the child was declared dead at the scene.
"The thoughts of our crews and staff across the entire Brigade are with the child's family at this difficult time."