Three children have escaped from a house fire in which people have died, police said.
The children, aged 13, 12 and 10, are being treated in hospital with non-life threatening injuries following the blaze at a remote property at Llangammarch Wells, Powys.
Dyfed Powys Police said they received reports from the Mid and West Wales Fire and Rescue Service shortly after midnight.
"Upon arrival the house was ablaze and three children aged 13, 12 and 10 years were able to escape," a police spokesman said.
"They are being treated in hospital but do not have life threatening injuries.
"However, there are a number of people unaccounted for at this time and we can confirm that there are known to be fatalities.
"Due to the severity of damage at the scene we are unable at this stage to identify any of the deceased or confirm numbers.
"Specialist scientists and fire investigators are still assessing the scene prior to further investigation. At this time we are treating the cause of the fire as unexplained."
Kirsty Williams, AM for Brecon and Radnorshire, said: "This is devastating news in such a close-knit community.
"I'd like to express my deepest sympathies to those affected and thank the emergency services for their assistance."
County Councillor Tim Van-Rees, who represents the area, said: "I knew the family, not well, and I knew the father and several of the children.
"They were a large family, although I am not sure how many were living there.
"It is absolutely shocking and a devastating blow and it is possibly just as well we are in half-term at the moment because the effect on our children and the schools would have been very severe.
"I have spoken to the owner of the property who was alerted and telephoned the fire brigade and I must say as a member of the fire authority the local fire brigade were outstanding.
"I've had a full description from the fire commander and they risked life and limb to see whether anything could be done but unfortunately their efforts were not well rewarded.
"Speaking on behalf of the community our thoughts and prayers will all those affected. The community will come together and do all it can for the surviving children and relations."