A man and another child were treated for burns following the blaze at The Plantation in West Park Road, Newchapel, Surrey, during the early hours of this morning.
A Surrey Fire and Rescue Service spokesman said three crews attended reports of a blaze at the site at 1.37am.
He said: “The fire was extinguished using hose reels; however, three people – two children and an adult – have died.
“Surrey Fire Service and Surrey Police are carrying out a joint investigation and our thoughts are with their family and friends at this very sad time.”
Surrey Police said units were at the scene, which remains cordoned off while inquiries are carried out into the cause of the fire.
“Police were called to the site, off West Park Road, at around 1.45am today following reports that a mobile home was on fire.”Sadly three people, believed to be an adult and two children, have been declared dead at the scene.”
He said a man and another child were treated for burn injuries at the location and the child had since been taken to East Surrey Hospital in Redhill.
The spokesman added: “Surrey Police and Surrey Fire and Rescue units are currently at the scene, which remains cordoned off while inquiries to establish the circumstances surrounding the fire continue.”