A three-year-old boy was killed in a caravan fire in the early hours of Sunday morning.
His sibling, aged four, is in a critical but stable condition in hospital and his dad is stable.
The fire service said a touring caravan and vehicle were completely destroyed and adjacent property damaged in the blaze at Ffair Rhos, near Tregaron, Ceredigion.
Emergency services had been called to the scene at 05:35 GMT on Sunday.
“Enquiries so far lead us to believe that three people were inside the caravan at the time the fire broke out,” said Dyfed-Powys Police’s Det Ch Supt Steve Cockwell.
“These were a father and two children – a four-year-old, and a little boy who we believe to have been aged three.
“While the father and the eldest child were able to get out of the caravan, the younger of the siblings was tragically found deceased inside.”
Specialist officers are now supporting the family while a major incident room has been set up at Aberystwyth Police Station.
Det Ch Supt Cockwell added: “The father is currently in a stable condition in hospital, while the four-year-old is critical but stable.
“Both suffered burns.”
The Criminal Investigation Department is investigating the cause of the fire and an appeal was made for witnesses.
“This was a tragic incident, and we will be doing all we can to find answers for the family, whose world will have been torn apart by this morning’s events,” the officer added.
A spokeswoman for the Mid and West Wales Fire service said appliances from Tregaron, Aberystwyth and Lampeter attended.