Folk trying to help keep woodland clean and tidy were left upset after litter they had collected was set on fire.
Gerri Waring, who lives in Breck Road, Sprowston, set up a litter pick with three other people - including her husband Tony - to help clear Harrison's Wood and the Cottage Plantations in the town.
The rubbish, which included cans, bottles and even a rollator walking frame, was left strewn across the car park of the Cottage Plantations after the group's litter pick.
Mrs Waring, 59, said: "We held a litter pick between 10am and midday on Sunday.
"We collected between eight to 10 bags of rubbish overall and as per our instructions by Broadland council, we left the bags by the pedestrian bins for it to be collected.
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"Unfortunately, in the meantime, someone decided to set fire to them in the night.
"We're very disappointed that our efforts have been largely wasted.
"It's just pointlessly destructive and it shouldn't happen.
"I don't understand what must go through someone's head to do this and why they would think it's fun."
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A spokesman for Norfolk Fire and Rescue Service said: "One appliance from North Earlham attended a fire in the open along Blue Boar Lane at 8.45pm.
"Hose reel jets were used to extinguish the fire and the stop message was received at 9.01pm."
Despite the incident, Mrs Waring said she will not stop trying to help keep the community clean.
She added: "We will absolutely continue to do our litter picks.
"It won't put me off doing what I think is right - if anything it makes me more determined to carry on."
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