Police and fire officers are investigating after a blaze in a shed spread to the door of a flat.
Fire crews were called to the maisonette in Heywood Road in Savick, Preston at around 7.30am today.
They discovered a shed well alight, with flames having reached nearby accommodation.
A fire brigade spokesman said the fire was believed to have been started deliberately. As a result the police were informed.
Firefighters used a hosereel to put the blaze out annd used a thermal imaging camera to check for smouldering hot spots. No-one was injured.