Firefighters are tackling an "inferno" at a block of 20 flats after a huge gas explosion, with witnesses reporting people screaming and leaping from windows to escape the flames.
Neighbouring properties were evacuated from the residential area in Redwood Grove, Bedford in Bedfordshire, with one person confirmed to have died.
The victim, who has not been named, was found as emergency services searched the three-storey building.
Police say there is the "possibility" of more fatalities as they continue to search the site.
At least two further people have been taken to hospital, a deputy fire chief said.
One patient has a serious leg injury.
A firefighter was also treated at the scene for smoke inhalation.
Footage shared on social media shows flames erupting from the building as hero firefighters try to battle the blaze after neighbouring properties were evacuated.
Have you been caught up in the blaze? Email webnews@mirror.co.uk
Bedfordshire Fire and Rescue Service said the huge blaze was caused by a gas explosion. Members of the public have been advised to avoid the area.
Chris Bigland, deputy chief fire officer for Bedfordshire, said a gas stove - possibly used amid rising fuel costs - may have caused the explosion.
He said that 100 homes were evacuated this morning, of which around 36 have become unliveable due to fire damage.
Bigland confirmed that two people were in hospital due to the fire. He said a firefighter was also treated for smoke inhalation as a precaution.
He declined to provide further details on the victims, who are said to be male residents aged in their 20s and 50s.
John Murphy, chief superintendent of Bedfordshire Police said at a press conference: "At least one person is confirmed to have died.
"There's a possibility we may find more fatalities as we search the scene."
Local residents in Bedford described feeling the ground shake and seeing a person jumping from a second-floor window to escape the burning building.
"I heard the explosion from my house round the corner," said one resident, who wished to remain anonymous.
"I walked to town and saw the flames and also witnessed someone jump from the second-floor window whilst flames were blaring out."
Adrian Marz, who lives on the top floor of the neighbouring building, told how he and his partner rushed to "start knocking on people's doors" and help evacuate the area.
"When I was outside the building I saw the walls being torn apart... and all of the windows out, and smoke and flames pretty much instantly", he told the BBC.
"I saw a couple of people jump out of the building and started helping them out... bringing them away from the fire, away from the danger, but it was a very, very serious and very big explosion.
"We saw people jumping out from the flat that was directly affected. I think that was the flat that blew up, and that was where the gentleman jumped out and hurt his hip really badly. We pulled him away."
Adam Fisher, a 37-year-old sales worker whose office is nearby, said he heard a "huge explosion" before witnessing "an inferno" at the site and people screaming.
He said: "A huge explosion heard - everyone went to our work car park to see what was happening.
"Our building is adjacent to the apartment complex - immediately an inferno (was) visible, huge smoke cloud billowing, people screaming and people frantically calling for emergency services."
Another concerned member of the public reported hearing an explosion moments before spotting smoke coming from the area.
She said: "Was working in a shop nearby. Explosion shook the whole shop and the ones near us.
"Next thing we knew we could see smoke coming from Redwood Grove.
"Scary stuff."
Deputy fire officer Mr Bigland went on to say: "Gas wasn't linked to the building. There may have been gas bottles used for heating or cooking.
"It could have been a camping stove with the fuel crisis and rest of it. We can't rule it out - we just don't know."
He said that people had left the building by 'unconventional methods' and that firefighters had helped people to evacuate.
Bigland said: "When crews arrived people were looking to hang out of the building."
He added that fire crews were called at 9.20am to reports of a fire and explosion and arrived at the scene within six minutes.
A spokesman for the fire service previously said: "Bedfordshire Fire and Rescue Service are currently in attendance at a major gas explosion on Redwood Grove, Bedford.
"There are currently six appliances, two water carriers, an incident command unit at the scene.
"Please avoid the area and keep windows and doors closed."
The force of the flames "caused a large portion of the roof to collapse", according to a spokesman for the police force, who described a "significant fire".
The spokesman added: "We know people are keen to help, but would ask people to avoid the area and keep any doors and windows closed.
Meanwhile, they said an Emergency Assistance Centre has been set up at The John Bunyan Centre for people who have been evacuated and need support.
An adjacent block of flats has also been evacuated and we are working to get people back in their homes as quickly as possible.
A Magpas air ambulance landed near the scene and flew the patient with leg injuries to Addenbrooke’s Hospital, the service said in a statement.
East of England Ambulance Service added that the other patients were conveyed to Bedford Hospital South Wing.
A spokesperson said: "We were called at 9.33am today to a significant fire at a block of flats in Redwood Grove, Bedford.
"Three ambulances, the Hazardous Area Response Team, a tactical commander, three operations managers and the Magpas Air Ambulance were sent to the scene.
"One person was airlifted to Addenbrooke’s Hospital for treatment for leg injuries, while two people, one of whom was a firefighter, were conveyed to Bedford Hospital South Wing with smoke inhalation."
