Staff have regained control after serious disturbances broke out at Northern Ireland's high security Maghaberry jail.
A prison office was burned out during the trouble
A fire was started in Bann House shortly after 1930 GMT on Wednesday and was dealt with quickly by the fire brigade.
During the incident, 35 loyalist prisoners barricaded themselves inside a wing of the prison, where loyalist and republican inmates have already been separated on a temporary basis.
As the violence continued, Army technical officers were called in to deal with a suspect device which had been strapped to a grille.
It was later declared an elaborate hoax.
Sixteen prison officers are being treated for shock and the effects of breathing in smoke.
Prison officers said some prisoners used cigarette lighter fuel to make improvised petrol bombs during the trouble.
They eventually returned to their cells shortly before 0600 GMT on Thursday.
Chairman of the Prison Officers' Association at Maghaberry Markus Lewis said the prisoners caused extensive damage.
"Basically, these people have gone on a rampage of wanton destruction," he said.
"They have destroyed fridges, cookers, microwave ovens, food servery units, and two snooker tables provided for their own recreational purposes.
"They have gutted, by fire, an office with all its equipment. They have smashed up table tennis units, and televisions.
"These things are all provided by the tax payer for their enjoyment."
The Director General of the Northern Ireland Prison Service, Peter Russell,
said the rioting had put the lives of prisoners and staff at risk.
"It is to the great credit of the staff involved that it has concluded
without serious injury," he said.
All visits to the prison on Thursday have been cancelled.
Prison Officers' Association spokesman Finlay Spratt condemned those behind the disturbances, adding the incident was an example of the dangers prison officers face.
The violence followed talks between Northern Ireland's prison management and unions to avert strike action at jails across the UK, broke up for the night.
The discussions followed the threat of industrial action by prison officers angry over security arrangements at the homes of Northern Ireland staff.
On Tuesday it emerged up to £20,000 was being spent on security for each of the 1,400 prison officers whose details were discovered in the hands of the IRA.
It is illegal for prison officers to strike, but the union has insisted it will go ahead with the move anyway, without a ballot.
Prisons management, the union at local and national levels, prisons minister Jane Kennedy and Northern Ireland Secretary Paul Murphy took part in Wednesday's talks in London.
They discussed the security response which followed the discovery in October 2002 that the IRA had acquired the personal details of many officers.
Jane Kennedy said no more money was available for security
However, the union says the money being spent on security measures at many of their members' homes is not enough.
The talks are set to resume on Thursday afternoon.
A Prisons Service spokeswoman said the meeting was "useful and constructive" and it had focused on staff safety.
Mr Spratt said the discussions had been constructive and that he hoped a conclusion could be reached.
Industrial action was threatened in October following attacks on five members of staff at Maghaberry.
A number of homes of serving and former prison officers have also been attacked.
These attacks were linked to a prisoners' dispute at the jail.
In September, a review of safety at Maghaberry recommended separating republican and loyalist prisoners.
The move was introduced in the wake of violent clashes between rival groups in the jail and in the face of a "dirty protest" by a group of dissident republican prisoners.
As well as paramilitary prisoners, Maghaberry houses male and female prisoners, whether they are convicted or on remand, and a number of asylum seekers.