Two children and two adults have been killed after a fire broke out at a house in North Wingfield in Derbyshire.
A third child was being treated for minor injuries in hospital following the blaze at an address on Williamthorpe Road, around four miles south of the centre of Chesterfield.
A joint investigation was being carried out by the police and fire service. Police said the area would be closed off for several hours and local diversions were in operation.
A neighbour told the BBC she had "heard next door thumping and banging" before the emergency services arrived.
A spokesperson for Derbyshire Fire and Rescue service said: "It is with regret that Derbyshire Fire and Rescue Service can report that at 04.58 hours, the service was called to attend a serious house fire where tragically four people lost their lives.
"Derbyshire Fire and Rescue Service would like to extend its thoughts and sympathy to the family and friends of the deceased."