A nine-year-old boy has died and two young girls are in hospital after a house fire early on Tuesday, police said.
The three children are believed to be from the same family.
Fire crews were called to the terraced property in Altonhill Avenue, Kilmarnock at around 3.19am.
They found a "well developed" fire on both floors of the two storey building and were told that people may still be inside.
Rescue teams found two girls and a young boy on the upper floor after fighting through "intense heat and thick acrid smoke" to reach them.
After rescuing the children they gave them trauma care for varying degrees of smoke inhalation until paramedics took over.
The youngsters were then taken to Crosshouse Hospital in Kilmarnock where the boy died.
The girls, aged three and four, are said to be in a "stable" condition.
Strathclyde Fire and Rescue's area commander Ally Boyle said: "Our thoughts and prayers are with the boy's family at this sad time."
A specialist fire investigation team will carry out a joint inquiry with Strathclyde Police to determine the cause of the fire.
Strathclyde Police said that investigations were at an early stage.