Firefighters and paramedics were called out to a fire in Blackpool earlier, with one official confirming a person has died.
Emergency service workers were pictured in Althorp Close, off Talbot Road, alongside several police cars shortly after lunchtime today.
A police cordon was in place at around 1.15pm, with one neighbour saying there had been a fire in a flat and that he feared the worst.
Forensics experts dressed in white suits were seen at around 2pm, while detectives were spotted carrying out door-to-door enquiries.
Police later confirmed the body of a woman, thought to be in her 40s, was found inside the flat.
Her death is being treated as 'unexplained', detectives said, and her next-of-kin has been told of the tragedy. They are being supported by specially-trained police officers.
Det Insp Kathryn Riley, from Blackpool CID, said: "First and foremost our thoughts are with the family and friends of the woman who died.
"Her death is currently being treated as unexplained but an investigation has been launched and we will be working closely with the fire service to determine exactly what occurred.
"We will remain at the address overnight and into tomorrow. [Sunday]."
Fred Mulholland, 65, of Spencer Court, said: "Most of the buildings around here are sheltered accommodation so you don't get to see many people if they can't get out of their house.
"There can't have been a big fire because there isn't any damage to the windows but something serious must have gone on because the police have been door-to-door questioning."
Lynn Towers, 57, of Spencer Court, added: "It's terrible that someone has died. It's hard to believe that a fire has actually happened as it doesn't look like there is any damage."
And Henry Howe, 73, also of Spencer Court, said: "It's very tragic to hear someone is dead. I didn't see anything until the fire service arrived. The sirens woke me up.
"That was midday, I think, and then the police also arrived later on and put tape around the flats. I think you consciously know something terrible has happened when you see that."
In a statement, the Lancashire Fire and Rescue Service (LFRS) said: "Three fire engines from South Shore, St Annes, and Fleetwood attended a fire in a flat on Althorp Close in Blackpool.
"There was one casualty. An investigation into the cause of the fire is underway."
The South Shore fire engine, which was in the area, arrived six minutes after being called at 12.34pm, a spokeswoman said.
A spokeswoman for the North West Ambulance Service (NWAS) said she was unable to say anything other than paramedics attended the scene.