Police called to a house in Newhaven at 12.05am on Wednesday (October, 30) following reports of a fire are treating it as deliberate.
Police believe that it was caused by the deliberate ignition to a mattress which was left down the side of the house.
The fire then spread to the building and caused extensive damage.
Officers said the three people inside, a woman and two men, were able to escape the property in Lee Way unharmed with their three dogs.
The fire is being investigated as an incident of arson, no arrests have been made.
DC Bradley Stadler said:
“Anyone who witnessed any suspicious behaviour in the area at this time is asked to report online or call us.”
Anyone with information is asked to call 101 quoting serial 8 of 30/10.