More than 50 inmates reportedly took over part of a prison wing. The incident broke out at HMP Northumberland in Morpeth at around 7.30pm yesterday.
Prison Officers Association general secretary Steve Gillan told the BBC that there was a stand-off. He said last night: "We do not know what has sparked this major incident, but I do know that 50 plus inmates have taken over a wing," he said.
"We have teams from other establishments trained to deal with riots on their way. There is concerted indiscipline and our officers will try to contain it."
A spokesman for Sodexo, which operates the prison, said the situation has now been resolved and an investigation is due to be carried out into the incident.
Inmates are reported to have taken over part of a prison wing. Officials at HMP Northumberland confirmed a "disturbance" was under way, but dismissed as "speculation" the suggestion of a stand-off between inmates and guards.
A spokesman for Sodexo, which operates the prison, said: "We can confirm there is a disturbance at HMP Northumberland.
"It is confined to part of one wing of the prison and we are working to resolve the situation as quickly as possible."
The incident has been ongoing since around 7.30pm. The Sodexo spokesman added: "It is not quite resolved yet."
Thieves who stole wedding flowers worth £1,000, including the bride's bouquet, have been branded "heartless" by police.
The break-in at East Heddon, Northumberland, was reported this morning - just hours before the couple were due to marry.
Sergeant Mick Quinn of Northumbria Police said, "The people who stole these flowers will have been well aware they were to be used for a wedding, and to steal them is completely heartless and thoughtless".
Our advice is - just because it says 'legal' on the packet does not mean it is safe. These products are usually made from chemicals that can have a serious effect on your health.
People appear to be suffering some particularly nasty side effects to this substance, Salvia, and we are concerned that there appears to be a quantity of it circulating in the Ashington area at this time.
If you are in possession of this substance do not use it - and if you have taken it seek medical assistance at once.