East Sussex Fire and Rescue Service is currently attending an ongoing incident at Lewes Prison.
A spokesperson said firefighters had been called following reports of a blaze in a cell.
The alarm was raised shortly after 4pm today (Thursday, March 7).
Fire engines from Lewes and Brighton are currently at the scene, said the spokesperson.
At 6.30pm, a prison service spokesman said the fire was put out before firefighters arrived and no-one was injured.