"He never regained consciousness following his injury on Tuesday.
"He was not in pain before he passed and was surrounded by his family and close friends.
"As a cricket community we mourn his loss and extend our deepest sympathies to Phillips family and friends at this incredibly sad time.
"Cricket Australia kindly asks that the privacy of the Hughes family, players and staff be respected."
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Hughes, 25, suffered the injury when hit by in the head by a bouncer from NSW paceman Sean Abbott while batting for South Australia in the Sheffield Shield match at the SCG on Tuesday.
Australian cricketers Brad Haddin and Aaron Finch arrive at St Vincent's Hospital in Sydney. Photo / Getty
He underwent emergency surgery to reduce pressure on his brain later that day and remained in an induced coma in intensive care. As the cricket world came to grips with the severity of his plight, numerous test and state cricket colleagues and friends joined his family at the hospital over the two days.
Test captain and close friend Michael Clarke was a near constant visitor, arriving back at the hospital just after 6am on Thursday, barely hours after he left the Darlinghurst facility on Wednesday night. A steady stream of sombre-looking current and former players followed him throughout the day.
Mid-morning interstate players Matthew Wade and Aaron Finch, who embraced Brad Haddin as he walked through the hospital doors, arrived.
After visiting the SCG, ashen-faced Australian cricket team coach Darren Lehmann arrived, returning again after midday.
Tom Cooper, the player batting with Hughes when he was hit, turned up after lunch and met Test opener David Warner outside the foyer where an increasing group of cricketers was gathered.
Some of the biggest names in Australian cricket arrived after 1pm to show their support, including former captain Rick Ponting, and Steve Waugh.
Test player Peter Siddle and James Pattinson were also part of the bedside vigil.
Broadcaster Alan Jones, a friend of Hughes, said on his 2GB radio programme today that he had been told that the "neurology is very, very bad, or in the language that the layman understands, the brain is very sick".
Jones, who is a Sydney Cricket Ground trustee, went on: "What happened is that the blow from the cricket ball damaged ... a major artery in the back of his head and that caused bleeding over the skull and prevented blood from going to the brain."
Writing in The Australian, senior cricket writer Peter Lalor said he was a talented cricketer who was liked by a wide range of sports people.
"The batsman may not have had the greatest technique, but his work ethic and attitude were impeccable. Senior cricketers and coaches embraced him with the sort of affection you rarely see among professional players ...
"Hughes was at the centre of almost every meeting for coffee or dinner on the long, empty days spent in international locations between games."
Australian fast-bowling great Glenn McGrath said, "Such terrible news with the passing of Phil Hughes. Our deepest sympathies to his family."
Australian cricket coach Darren Lehman tweeted shortly after the announcement: "RIP you little champ, we are all going to miss you ! Love, prayers to all the Hughes family xxxx"
The threat of express bowlers
Cricket at the highest level is indisputably a much safer game than in the pre-helmets era when bowlers were also often aided by uncovered pitches.
But the threat of serious injury - or much worse - posed by express bowlers to even the best of batsmen is still never far from the surface.
Even so, fatalities on the cricket field at the elite level are very rare.
In 1998, Indian Raman Lamba died when he was struck on the head by the ball while fielding at short leg without a helmet.
Pakistani wicketkeeper Abdul Aziz died while batting after being hit over the heart in the 1958-59 Quaid-e-Azam Trophy final, while Lancashire's Ian Folley passed away in 1993 after being struck in the head while playing for Whitehaven.
Earlier this month, Hughes' former NSW teammate Ben Rohrer was felled by a savage bouncer by Victorian quick Chris Tremain.
At first sight it looked every bit as bad as the blow that struck Hughes, Rohrer staggering and dropping to the side of the pitch.
He was taken from the field on a stretcher, sent to hospital for scans and left with a nasty welt under his ear - but Rohrer was cleared of any serious damage and was available to play again.
Tragically, Hughes won't get the chance to do the same.
Destined for great things
Great things were predicted virtually from the moment Hughes made his first-class debut for NSW at the age of 18.
After becoming the youngest batsman ever to make two centuries in the same test - achieving the feat away to South Africa as a 20-year-old in 2009 - some respected judges drew similarities between Hughes and the great Don Bradman.
The pair hailed from the bush - Hughes from Macksville on the NSW north coast, Bradman from Bowral.
Both were short men who boasted unusual techniques and an insatiable appetite for runs.
At the time, Hughes' average of 87.50 was almost in the realm of the Don's iconic 99.94.
But despite Hughes' rare talent, those numbers were never going to be sustainable over the long term for anyone whose surname wasn't Bradman.
Hughes' on-field struggles saw him in and out of the test squad over the subsequent five years, as his average dropped to 32.66.
At one stage he was dropped after being dismissed four times in as many innings in near identical fashion by New Zealand paceman Chris Martin.
His strength, playing so daringly outside off-stump, also became his weakness; opposing Test teams stacking fielders behind the wicket and giving him little width until he almost invariably slashed at one ball too many.
The most recent of his 26 tests was against England in mid-2013.
- additional reporting AAP