An inmate has been arrested after a fire at on the roof of a prison forced the evacuation of 64 prisoners.
The 29-year-old allegedly clambered on to the pitched roof of one of the house blocks at HMP Guys Marsh on Friday and started the blaze.
It caused damage to the Shaftesbury site and inmates in the block had to be taken to a secure area.
Dorset Police has arrested the prisoner on suspicion of arson with intent to endanger life.
It took 21 fire engines to get the fire under control.