Emergency crews were called out to tackle a fire in the car park of HMP Nottingham during the early hours of Saturday, May 11.
A spokesman for the Fire Service said crews from Arnold and Stockhill were at the scene from 12.14am until 1.06am on Saturday, May 11.
The prison is in Perry Road, Sherwood.
The spokesman confirmed the fire was in the car park and cars were alight.
An investigation is underway into the cause of the blaze.
A Prison Service spokeswoman said: "The fire service successfully resolved an incident in the grounds of HMP Nottingham early this morning.
"While no one was harmed, the safety and security of our staff is our priority and we are working closely with the police to urgently investigate what happened."
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