Crews were called to three fires started in quick succession in York last night (Sunday).
The first call came at 7.34pm, when a crew from Acomb responded to reports of a fire in a field.
A North Yorkshire Fire & Rescue Service spokesperson said: “This was found to be a mattress that had been ignited deliberately.
“Crew extinguished using a knapsack sprayer.”
Then at 7.40pm York firefighters put out rubbish on fire in a field.
Finally, at 7.58pm, the Acomb crew responded to reports of a small fire in woodland.
The spokesperson said: “The crew found this to be a settee on fire. Crew used a knapsack sprayer to extinguish.”