About 11am, Hurrell, Browne and the victim were all pacing around a shared day room at the prison.
"Then, in an entirely unprovoked way, you Mr Browne, struck [victim] in the face with a prison shank. It had been fashioned from a thin piece of metal," Justice Moore said.
"[Victim] fell to the ground. He rolled onto his back and lifted his legs defensively. He
tried to get back on his feet. But you kicked him in the head."
Hurrell then ran over to the victim, pulling out a shank of his own.
Together with Browne, they began kicking and stomping on the victim's head.
"[Hurrell] stabbed [victim] in the head and face with the shank about nine times. You finished your assault with three or four more stomps to [victim's] head.
"During this time you, Mr Browne, restrained B by sitting on his chest. You used your shank to saw across his neck."
Browne only stopped his attack when the prison guards intervened.
"Unsurprisingly, [victim] sustained life-threatening injuries... he also suffered several puncture wounds to his face and multiple bone fractures to his cheek bones and facial area."
Hurrell, 21, earlier accepted a sentence indication with a nine-and-a-half-year starting point, while Browne's counsel also called for the same starting point.
However, the Crown submitted that Browne had a "more serious and significant role" than Hurrell as he continued to attack the victim for about 20 seconds while Hurrell "disengaged".
The Crown pushed for a starting point of 10.5 years' imprisonment.
In handing down his sentence, Justice Moore said the shank "was not a weapon of opportunity".
"It was created and carried for the purpose of inflicting injury on another... the use of a shank indicates some level of planning to attack someone. Whether you fabricated the
shank anticipating this particular attack is uncertain."
Targeting the victim's head and neck in the way they did was "highly aggravating" and he agreed with the Crown that Browne's role in the attack "is properly characterised as extreme and prolonged", coming to a 10-year starting point before offering any discounts.
On a charge of wounding with intent to cause grievous bodily harm, Moore sentenced Hurrell to four years and four months, to be served on top of his current sentence.
Browne was sentenced to five years and four months' jail on the same charge.
'Background and circumstances lead to destructive path of crime'
Both accused had Section 27 cultural reports previously prepared to outline their backgrounds.
Hurrell is serving prison sentences for manslaughter, burglary, injuring with intent to injure, assaulting police, and intentional damage and he became eligible for parole on June 7, 2019.
It was revealed neither his mother nor father provided him any support during his childhood. They separated when he was young, and his father was the head of the Hastings Chapter of the Mongrel Mob.
He lived with his mother, who struggled with alcohol addiction, and at age 5 he was uplifted and put into CYFS care.
After moving around many carers, he was adopted by the Hurrell family, but he eventually left and from age 13 "turned to crime to survive".
He left school with no qualifications, having been expelled from two primary schools and one intermediate school.
From between the ages of 9 and 11, he began using substances to cope including synthetic cannabis.
Justice Moore noted the reports didn't attempt to draw a link between his background and the offending, as Hurrell's was written in 2018.
However, he said it was "clear to me that your background and circumstances inextricably led you down a destructive path of offending and institutionalisation".
'Institutionalised from age 14'
Browne had originally faced a charge of attempted murder, but the Crown offered no evidence at sentencing today.
He is currently serving sentences for aggravated robbery, three counts of burglary, two counts of injuring with intent to injure, arson, assaulting a prison officer, and resisting police.
He described having a "good childhood", despite having an unsettled upbringing.
His parents separated when he was 9 months old, but he was never abused.
Browne's father was "a functioning alcoholic" who told the report writer he tried to be a good dad and despite drink-driving convictions had worked hard all his life.
He and Browne's former partner had friends who were in gangs and when they
hosted parties, Browne sometimes saw their friends drinking and fighting.
He struggled at school because of ADHD and was helped to read and write thanks to his grandmother.
By the time he was 12 he had his first run-in with police for shoplifting and by 13 he began using synthetic cannabis.
Thefts and burglaries intensified to fund his habit before he joined a gang, and by 14 he was using methamphetamine and soon became addicted.
"From that point on you became institutionalised. You were in and out of youth justice facilities and were eventually imprisoned."