UPDATE: Cessnock prison officers are being praised for their quick-thinking following two separate cell fires yesterday.
Guards managed to extinguish the first fire and get the inmate to safety, before dealing with a second fire in a nearby cell.
The two inmates responsible have been moved to maximum security and will face charges.
"These officers put their own safety on the line to swiftly and professionally contain these two fires and their efforts should be applauded," Corrective Services NSW Commissioner Peter Severin said.
"The incident reports show that it was the officers' experience, good communication and coordination, which resulted in no injuries to staff or inmates. I thank them for their good service."
EARLIER: It was tense moment for guards at Cessnock Correctional Centre, after they were forced to extinguish fires that were deliberately lit in two separate cells.
They managed to put the flames out before firefighters arrived, just before 5:30pm Sunday afternoon.
A Fire and Rescue NSW spokesperson said the fires were extinguished "fairly quickly."
The cells didn't suffer any structural damage, only superficial damage.
No one was injured.
An investigation is now underway into the fires.