A man fell to his death from a burning block of flats after police arrived to look for a suspected arsonist.
Five officers tried to get inside the property to rescue the man, in his 50s, but were overcome by the flames, police said.
One officer sustained serious burns and remained in hospital on Friday. The others were treated for “minor injuries and smoke inhalation” and discharged, while a firefighter was treated by paramedics at the scene, Bedfordshire police said.
Detectives had been investigating three attempted arson attacks on properties in Luton in the early hours of Wednesday and used CCTV footage to identify a suspect.
The officers were dispatched to the apartment in Green Court, in a 15-storey block, at around 4am on Thursday but arrived to find the entrance on fire.
Emergency services were called but police said the “fire took further hold of the flat” before the man fell from a window.
Assistant chief constable Sharn Basra said: “This is a tragic case and we are working hard to establish all of the facts of what took place.
“Our focus on Thursday was on identifying the man who had died and tracing his family members before we released any further information publicly.
“We have also been carefully recovering all possible evidence from the scene and assisting residents who had been displaced from their homes. What is clear from the evidence collected so far is the bravery of the attending officer, who tried to fight through the flames to save the man inside.
“Our thoughts remain with both him as he recovers in hospital and the loved ones of the man who sadly died.”
The man has yet to be formally identified and his next of kin have been informed, the force added.
The case has been referred to the Independent Office for Police Conduct. More than 100 residents were evacuated from the building on Thursday morning, with the majority allowed back into their flats by the evening.
Luton council said there is no indication that cladding was a factor in the fire.
The Bedfordshire fire and rescue service area commander, Stuart Auger, said: “The fire was successfully contained to the flat thanks to the efficient performance of the building’s fire protection measures and fire doors.
“Thanks to this we were able to work alongside Bedfordshire police to efficiently evacuate all residents from the building with the help of smoke hoods.
“Our thoughts are with the loved ones of the person who sadly passed away and we will work with partners to reassure the community over the coming weeks and months.”
Anyone with information which may assist the police investigation is asked to call 101 or get in touch with the force through beds.police.uk/ro/report, quoting Operation Cheagle.