Crews from Whitby and Lythe dealt with two piles of rubbish on fire on a public footpath off Mayfield Road at around 7.30pm last night (Monday March 20).
One of the fires contained eight small cylinders which had all exploded before North Yorkshire Fire and Rescue Service arrived.
The second fire involved a 15kg propane cylinder which fortunately did not explode.
A spokesperson for North Yorkshire Fire and Rescue Service said: "The crew used water backpacks to extinguish the fire and cool the cylinder, lighting and a thermal imaging camera.
"The cause is believed to be deliberate."
Just over an hour later a crew from Whitby was called to a bin fire in the open in Airy Hill, Whitby, at around 8.40pm.
Again the cause is believed to be deliberate.