Video showed a mattress on fire at the side of a road, with flames having spread to bushes.
It was recorded by passer-by Atiq Rehman in Eastfield Road in Peterborough at about 22:50 GMT on Monday.
Another man is seen dragging the mattress away from the bushes. Mr Rehman said the fire “could have been much worse” as it was close to people’s homes.
Cambridgeshire Fire and Rescue Service said the blaze was believed to have been started deliberately, and an investigation was under way.
