The Prison Service in the UK is to launch an investigation after a riot at Bedford Prison which reportedly saw up to 200 inmates go on the rampage.
The disturbance was "successfully resolved" late on Sunday night after riot officers spent more than six hours trying to bring the disorder under control.
Scores of prisoners flooded the jail's gangways in chaotic scenes after the disturbance broke out shortly after 5pm.
A Prison Service spokesman said: "Specially trained prison officers and staff from the emergency services have successfully resolved an incident involving a number of prisoners at HMP Bedford.
"An investigation into this incident will take place. We are absolutely clear that prisoners who behave in this way will be punished and could spend significantly longer behind bars."
There were no injuries to prison staff but two inmates were treated for injuries that were not thought to be serious.
Richard Fuller, MP for Bedford and Kempston, will put an "urgent question" to Justice Secretary Liz Truss in Parliament on Monday, local media reported.
Specialist riot officers were deployed at the category B prison in Bedford town centre after the riot broke out on Sunday afternoon, with police cordoning off an area outside and emergency services on stand-by.
Steve Gillan, general secretary of the Prison Officers Association (POA) said some guards were forced to retreat to a "safe place" while large numbers of prisoners ran amok.
Sources said the riot spread over more than wing inside the prison, and footage supposedly from inside the facility - though unverified - posted online revealed chaotic scenes with scores of prisoners shouting and bellowing in walkways and gangways.
At around 11pm, about half an hour before the riot was brought under control, there were reports of loud bangs or explosions coming from inside the prison.
The disorder comes after the head of the POA Mike Rolfe last week warned British jails had been engulfed by a "bloodbath".
Mr Gillan said: "The POA has been warning about this situation of violence in our prisons - it would appear it's coming to fruition.
"I just hope there's no prisoners or indeed prison officers injured in the violence."
HMP Bedford, which has been on its current site since 1801, currently holds around 500 inmates, according to a HM Inspectorate of Prisons report in September.
The watchdog's report found inmates claimed it was easier to get drugs than clothes or bedsheets at a prison where standards had deteriorated to "unacceptable levels".
A survey found the number of prisoners saying it was easy or very easy to get drugs had almost doubled since the last inspection of the jail in February 2014.
The number saying they had developed a drug problem while at the prison increased from 4% to 14%.
The HMP inspection in May also found that the physical condition of the prison was poor, with many inmates living in cramped conditions. The report detailed damaged furniture, graffiti, shortages of clothing and dirty, unscreened showers.
The report also said: "Arrangements for managing violent and bullying behaviour and supporting victims were weak."
Britain's shadow justice secretary Richard Burgon said on Twitter: "More troubling news concerning our prisons. The Justice Secretary needs to do more urgently to tackle crisis."
More troubling news concerning our prisons. The Justice Secretary needs to do more urgently to tackle crisis https://t.co/lAsSLUAQRT— Richard Burgon MP (@RichardBurgon) November 6, 2016