Extraordinary moment 100 riot officers were forced to take down 20-stone rampaging prisoner after he smacked guard with a pan, set fire to kitchen and ran amok for eight hours
- Officers threw pyrotechnics and used Pava spray to distract the 6ft 2in convict
- They tried to bring him under control during eight-hour riot at HMP Full Sutton
- John Onyenaychi, 38, is a knifeman who tried to kill two police officers in 2010
- Onyenaychi was jailed for further 81 months to be served after his 25-year tariff
This is the moment a dangerous inmate weighing nearly 20 stone attacked prison guards during a 'rampage' that took 100 officers in riot gear to stop.
The officers threw pyrotechnics and used Pava spray to distract the 6ft 2in convict as they attempted to bring him under control during a shocking eight-hour riot.
The mayhem involved John Onyenaychi, 38, a knifeman who tried to kill two police officers in Ealing, West London, while on licence from prison in December 2010.
Onyenaychi, whom police once described as one of Britain's most dangerous men, caused £15,000 of damage at the top-security HMP Full Sutton in East Yorkshire.
Shocking footage filmed by CCTV cameras inside the jail shows Onyenaychi hitting an officer over the head with a pan from behind while he was unlocking a gate.
His keys were still in the lock as Onyenaychi struck him or attempted to strike him a further five times, causing the key chain to snap as the officer slumped down.
The prisoner then struck out at other staff, and is said to have hit a female officer and narrowly missed another.
As it developed, another inmate is said to have removed the keys from the lock and placed them in a bin, where Onyenaychi later retrieved them.

Prison officers attempted to bring John Onyenaychi under control during an eight-hour riot
Onyemaechi also started a fire in a kitchen, on which he put cloth, magazines and then a chair, which can be seen in the footage.

Onyenaychi was previously described as one of the most dangerous men in Britain
But the smoke meant nothing more could be seen from that camera. Onyenaychi can be seen laughing at the fire, which staff had to put out with a mobile appliance after breaking a window.
Onyenaychi was finally restrained after evading his legion of pursuers by running across netting between two landings which he then fell through, although he managed to get up and briefly walk away.
He had caused £15,000 of damage after starting two fires and attacking officers with an improvised weapon as well as the 'heavy' pan. The Prison Mutiny Act also had to be read over the tannoy 'instructing all prisoners to return to their cells' during the incident.
Onyenaychi was serving a double life sentence at the time of the attack on August 9 last year.
He had been jailed at the Old Bailey in 2011 for a minimum of 25 years for two offences of attempted murder, attempting to wound to resist lawful apprehension, robbery, and wounding with intent to do grievous bodily harm.

The 'rampage' at HMP Full Sutton in East Yorkshire that took 100 guards in riot gear to stop
In Onyenaychi's sentencing hearing earlier this month at Hull Crown Court, Anthony Dunne, prosecuting, said in the days leading up to the outbreak staff had become 'increasingly concerned' about his behaviour.
'His size and demeanour made him intimidating to prison staff and other prisoners,' Mr Dunne said.
Concerns had led to a discussion with the custodial manager on Echo Wing, where Onyenaychi was held, about him being transferred, which caused him to become 'agitated' and 'upset his behaviour was being challenged in this way'.
Trouble began when Onyenaychi asked to go into a 'sterile' area on the wing where cooking and cleaning equipment was kept. About ten minutes of CCTV from inside the jail was played in court, some of which is shown in the video above.
Onyenaychi told one officer: 'Get off this landing now or I'm going to kill you,' - the first of two death threats he made.

Onyemaechi also started a fire in a kitchen, on which he put cloth, magazines and then a chair
Onyenaychi caused facial cuts to another officer when he smashed a window, showering him with glass. He also injured another when he 'lashed out' with a 10cm screw or nail.
As well as the fire in the kitchen, he started another blaze, which was 'controlled' by the fire brigade, by which time the prison service escalated the incident to national level, leading to 100 officers attending in 'full personal protective' equipment.
The officers threw pyrotechnics and used Pava spray to distract Onyenaychi as they attempted to bring him under control. He was eventually restrained and taken to the segregation unit.
The custodial manager on the wing, who had 20 years' experience, said it was 'the most frightening experience she had ever witnessed'.
Among the injuries to those involved in the initial disturbance were two broken bones in an officer's right hand, which left him unable to help his wife with their nine-week-old baby.

The officers threw pyrotechnics and used Pava spray to distract Onyenaychi during the riot
Onyenaychi admitted assault occasioning actual bodily harm, four counts of common assault, two of making threats to kill, affray, and arson being reckless as to whether life is endangered.
Anya Lewis, for Onyenaychi, who appeared over a video link from HMP Woodhill in Milton Keynes, said he had been concerned about the effect of a prescribed steroid on his mood, and had raised this before and after the incident, when he said he did not want to take it again.
Onyenaychi was jailed for a further 81 months to be served after his 25-year tariff.
Judge David Tremberg told him: 'You are clearly a powerful man, you went on the rampage and you cared little for your own safety, let alone that of others.'
Onyenaychi can only be released when the Parole Board deems he is no longer a danger to the public.