A woman has been arrested on suspicion of ABH against a 90-year-old in a sheltered housing complex.
Emergency services were called to Stopford Court on Sparth Road in Clayton-le-Moors at 1am on Thursday, February 9.
Two fire crews from Hyndburn attended to put out a kitchen fire in a flat.
Firefighters said a pensioner required first aid from paramedics to a head injury and smoke inhalation before being taken to Royal Blackburn Hospital.
A Hyndburn fire station spokesperson said: “The fire is being treated as suspicious and is under investigation by police and the fire service.”
Lancashire Police said a 46-year-old woman from Accrington has been arrested on suspicion of ABH and remains in custody.
No residents were evacuated from the sheltered housing complex as a result of the fire.