Crews from Alnwick, Belford and Seahouses attended the blaze after being called to the corner of North Street and Taylor Street, Seahouses, shortly before 1.30am on Tuesday, March 10.
Additional firefighters from Alnwick and Berwick were later sent to the scene.
Tyne and Wear Fire and Rescue Service attended with its Aerial Ladder Platform, while a response from Northern Powergrid and Northern Gas Networks was also requested.
Northumberland Fire and Rescue Service confirmed on its Twitter account that an investigation has been launched into the incident.
A spokeswoman from the service confirmed to the Gazette shortly before 10.30am that investigators remained on the scene.
A Northumbria Police spokesperson added: “Both occupants of the house were out at the time of the fire and there were no injuries.
“The property did, however, receive extensive damage, as did neighbouring properties.”