Fire crews from three Sunderland stations were called to a blaze which caused serious damage to a house in Pallion.
Appliances from Sunderland Central, Farringdon and Marley Park stations attended at the house in Florida Street at lunchtime today.
The blaze, which started in the rear yard of the vacant property, is being treated as suspicious.
It took crews the best part of an hour to extinguish the fire.
Firefighters used sophisticated cutting equipment to make their way into the roof space of the cottage in order to make sure the fire had not spread to the neighbouring property.
Watch manager Don McAneny, from Sunderland Central Fire Station, was the first senior officer on the scene and described what had happened.
We have a fire that has initially started in the back yard of the house in rubbish and building materials. It has then spread to the ground floor of the end terrace cottage and then, unfortunately, it has spread through the roof.Watch Manager Don McAneny
“We have a fire that has initially started in the back yard of the house in rubbish and building materials,” he said.
“It has then spread to the ground floor of the end terrace cottage.
“And then, unfortunately, it has spread through the roof.”
Two appliances had attended at first, with a third called in later as the full extent of the incident became clear.
“We used four breathing apparatus, three hose reels and our positive pressure ventilation fan,” said watch manager McAneny.
“And we used our Cobra cold cutting lance - that gave us access to the roof because we were concerned it had spread through to next door.”
Cobra equipment uses a mixture of water and a cutting agent which is ejected through a special nozzle on a lance at high pressure to cut very quickly through construction materials.
The method allows a blaze to be fought from outside through a penetration hole which is so small no oxygen is admitted to the fire.
The cause of the blaze is unclear: “It is going to be investigated because it is suspicious,” said Watch Manager McAneny.
“We have had reports from neighbours that there were signs of smouldering as early as nine this morning but we were called at 13.01.
“It took us 45 minutes to get it under control.
“There were initially two appliances, then we asked for the extra one.”
A spokesman for Tyne and Wear Fire and Rescue Service said ten calls had been received from members of the public about the blaze.