A major woodland fire near Darwen may have been started by "neglectful and reckless" youths, according to firefighters at the scene.
Crews found a camping shelter, a campfire, and cans of beer at the origin of the blaze.
Shaun Walton, a group manager at Lancashire Fire and Rescue Service, posted about the discovery on Twitter.
His post read: "Egerton wildfire most probably caused by neglectful and reckless actions by youths with campfire located at origin.
"Disappointing to find a camping shelter and other paraphernalia on scene as well."
Several fire engines - three from Greater Manchester - and around 45 firefighters were called to a large woodland fire at around 12.10pm on Tuesday.
Shortly after 3pm, Lancashire Fire and Rescue issued an update on the incident, saying that crews had managed to reduce the fire to a 100m area.
A "significant number" of trees were involved, which makes the fire more challenging and will see crews there for some time.
It follows a huge gathering of people near the incident last week, who broke lockdown rules to have a party at Stoney Bank Lake and created a huge mess.
Crews urged people in the area to keep their doors and windows closed as the blaze has emitted a large plume of smoke.
We currently are in attendance at a moorland fire between Darwen and Egerton alongside crews from @manchesterfire. There is a significant smoke plume in the area so please be advised if you are in the area to keep your windows and doors closed as a precaution
— Lancashire Fire (@LancashireFRS) May 27, 2020
A number of special appliances were deployed to help tackle the blaze, including the Lancashire Fire and Rescue Service drone which revealed the scale of the incident early on.
Lancashire Police officers were called to manage traffic and asked people not to drive on the A666 between Egerton and Belmont.
Firefighters have been warning about the risks of wildfires for weeks as the weather becomes increasingly hotter.
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