How elite prison service squad train for high-stake situations

Wielding a makeshift weapon and screaming threats, the furious prisoner holds a hostage in his cell.Desperate prison officers have tried negotiating, but all efforts have failed - leaving the life of the captive in imminent danger.The lights go off. Then, without warning, explosions rip through the air, before four officers storm in and wrestle the inmate to the ground.These are the high-stakes, high-drama situations the National Tactical Response Group (NTRG) specialises in.Dubbed 'the Prison Service's SAS', the elite unit is constantly on call to respond to incidents at jails and immigration detention centres across England and Wales, from riots, barricades and rooftop protests to terror attacks.The Daily Mail was given a rare insight into their work during a tour around the Oxfordshire headquarters of the Response and Resilience Unit (ORRU) - of which the NTRG forms one part.