Northumberland Fire and Rescue Service have began an investigation into the cause of a blaze on Simonside Hills.
In a tweet, the Fire Service said: “We currently have 2 fire engines in attendance at Simonside monitoring the incident and dealing with hot spots.
“An investigation into the cause is underway.”
Pictures show the extent of the fire which broke out near Joe’s Wood, Simonside Hills, on Monday, April 13 from the afternoon through to the evening.
Eight fire engines were all tacking the fire at its peak as crews worked tirelessly over the space of five hours to extinguish it.
A spokesman for the brigade said: “Great work from our firefighters who got on top off this really quickly over 100 hectares of tough terrain.”