Police said they were called to reports of a fire at around 10.30pm on Monday in Ingoldmells. The force said a woman and three of her children were able to make it out of the caravan at Sealands Caravan Park safely, but her fourth child, a two-year-old girl, has died.
The woman and three children received medical attention at hospital and have since been released.
Detective Inspector Jo Fortune, senior investigating officer, said: "This is a devastating incident for all involved. We are in the very early stages of our investigations and the circumstances which led to the fire are not yet clear.
"We will be working closely with specialist teams to understand what happened.
"We would like to appeal to anyone who was there last night and has not yet spoken to police to come forward, and for anyone with video footage to please share that with officers to add to our intelligence of the incident.
"This is particularly harrowing, with a family losing a child, and we'd ask that people remember those victims and not share footage online."
Around 50 people from caravans in the immediate area were asked to leave their vans and were able to go to emergency accommodation created at the Laver Leisure site.
There will be an investigation team on scene throughout the day while the police carry out the initial stages of the investigation.
More to follow...