Residents of flats had to jump from a window after arsonists set alight to a sofa outside the property.
Police are appealing for witnesses following the blaze at a property in Weston Walk, Corby.
Between 4am and 6am on Wednesday, November 13, a sofa was deliberately set on fire outside a first floor flat, trapping the occupants inside. The victims got out of the property by jumping from a window.
Speaking to the Telegraph today (Saturday) a neighbour said the owner of the flat had leapt from his window clutching a dog and had been unable to brace himself during his fall.
The man, who police said was 42-years-old, suffered back injuries and was taken to University Hospital Coventry.
Scaffolding has put up on a building adjacent to the blaze to allow roof repairs to be carried out.
Witnesses to the incident, or anyone with information, are asked to call Northamptonshire Police on 101. Alternatively, information can be given anonymously to Crimestoppers on 0800 555 111.
Telegraph photographer Alison Bagley made a video of the aftermath of the fire, above.