Two engines went to a two-storey terraced house in Balmoral Road just before 10pm on Monday, to an accidental fire involving an electrical heater in a ground floor bedroom.
Firefighters said the occupants were upstairs at the time of the fire and were warned by a smoke alarm, before escaping the house and calling 999.
Two firefighters wearing breathing apparatus and thermal imaging cameras put out the blaze using a hose reel. Ventilation units were also used.
A spokesman for Lancashire Fire and Rescue Service said an unattended electrical heater in the bedroom had ignited a cushion and spread to surrounding combustibles items.
There was severe fire damage to a skirting board, floorboards, a heater, a leather bag and a cushion.
There was also severe smoke damage to the front bedroom.
The spokesman said: “Keep portable heaters one metre away from furniture and other flammable items.
“Always switch heaters off if you are going to leave them unattended.
“Check cables are in good condition. If they are frayed or damaged don’t use them.”
For anyone who needs a free home fire safety check, contact www.lancsfirerescue.org.uk or call 0800169 11 25.