A serial arsonist is believed to have started a fire in a block of flats in Cambridgeshire.
Fire investigators said the fire, at Gayton Court in Peterborough, could easily have killed one or more of the occupants.
They believe it was the work of an arsonist who has started a series of fires.
Two fire crews were called to the flats at about 0400 BST on Sunday.
They found rubbish piled against the doorway and set alight.
The timing of the latest incident ties in with similar fires, believed to have been started deliberately, at that time in the morning.
Vigilante patrols
Police and fire chiefs have recently expressed concern about a series of arson attacks in the Westwood area of the city.
Although officers in the emergency services have been keen to urge caution on local vigilante patrols, they are now concerned that if the fire-raiser strikes again, someone could be killed.
An arson task force was set up in the county in February aimed at cutting the number of suspicious fires.
Figures published three months ago showed that between 2001 and 2002, two-thirds of all fires in Cambridgeshire were started deliberately.