A murder investigation is under way after nine people were taken to hospital following a fire in west London.
Police said they were called to an address in Berkley Avenue, Hounslow, just after 1am on Wednesday.
A 48-year-old woman died in hospital, while another woman, 40, remains in a life-threatening condition.
The others - six men and one woman - were discharged after treatment for minor injuries.
No arrests have been made.
Detective Chief Inspector Neil John said: "Our thoughts are first and foremost with the victim's family and loved ones at this extremely difficult time, as well as everyone who has been injured.
"Our enquiries are progressing at pace as we work to establish the full circumstances surrounding the fire, which we believe may have been started deliberately."
Anyone with information or video footage is asked to get in touch with police on 101. To stay anonymous, contact Crimestoppers on its website or on 0800 555111.
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