Update

The cricket community worldwide is in mourning today following the death of Phillip Joel Hughes, aged 25.

Cricket Australia announced the news with a statement from team doctor Peter Brukner.

Read more here.

Earlier

Phillip Hughes remains in a critical condition overnight in intensive care in a medically-induced coma following emergency surgery in a Sydney hospital.

Hughes collapsed at the wicket having been struck in the head by a bouncer in the West End Redbacks' Bupa Sheffield Shield match against the NSW Blues at the SCG.

Cricket Australia's Bupa Support Team Doctor, Dr Peter Brukner detailed a traumatic day for cricket.

"Phillip Hughes sustained a severe head injury while batting for South Australia at the SCG today," Dr Brukner said.

"Phillip was treated on the ground by Cricket NSW medical staff and transferred by Ambulance to St Vincent’s Hospital.

"He subsequently underwent surgery and remains in a critical condition in the hospital’s intensive care unit.

"Unless there is any significant change there will be no further updates on his condition until tomorrow.

"Phillip is receiving the best possible medical care. The thoughts of his teammates and the wider cricket community are with Phil and his family and friends at this difficult time.

"We ask that you kindly respect the family’s wishes for privacy."

We can confirm that Phillip Hughes is now out of surgery. He remains in a critical condition in ICU. Thank you for the well wishes. — St Vincent's Sydney (@SVHSydney) November 25, 2014

The next 24 to 48 hours will be crucial for Hughes as he will continue to be closely monitored by the hospital staff, with all thoughts turning to the batsman's welfare. The Sheffield Shield match has been abandoned by mutual agreement between both teams' captain and coach.

Hughes was struck on the back, lower left side of the head when he turned away as he followed through with an attempted pull-shot to a regulation short-pitched delivery from young NSW quick Sean Abbott.

No blame is attached to Abbott who was first on the scene to offer Hughes assistance. Abbott, along with all cricketers from both teams, have been offered counselling and support from Cricket Australia and the Australian Cricketers' Association.

Hughes was 63 not out when the incident occurred, as the left-hander swung at a bouncer and misjudged his shot, taking the brunt of the delivery on the lower left side of the back of his head.

The momentum of his follow through took Hughes to the side of the pitch where he rested momentarily looking at his feet, with one hand on his knee and propped up by his bat in his right hand. He then collapsed, falling face-first to the ground as the NSW players, fellow batsman Tom Cooper and umpires rushed to his aid.

Medical assistance was quickly on the scene, with NSW Blues team doctor and Cricket Australia's chief medical officer Dr John Orchard attending. Play was suspended with the score at 2-136 midway through the second session.

Hughes's mother and sister were in the stands at the SCG. They and SACA General Manager High Performance, Tim Nielsen, were with Hughes at St Vincent's, along with Dr Orchard.

Australia captain and close mate Michael Clarke soon arrived at the hospital to join the well-wishers.

Nielsen made a short statement outside the hospital: "As you're aware Phillip Hughes suffered an injury today and he's undergoing surgery. The outcome of that surgery is unlikely to be known for 24 to 48 hours. In the meantime we appreicate it if you look after family and friends and respect their privacy please."

Quick Single: Best wishes flood in for Hughes

Hughes was taken from the SCG field on a medicab, with NSW batsman and Australia squad teammate David Warner riding alongside his mate.

Thoughts are with my little mate Hughsy and his family. He is a fighter and a champion and he will get through this. Praying for you buddy. — David Warner (@davidwarner31) November 25, 2014

He was treated on the boundary by Dr Orchard and paramedics as three ambulances arrived at the SCG before a medivac helicopter landed on the outfield.

Hughes received mouth-to-mouth rescusitation and oxygen on the boundary line as teammates and police erected a white screen to shield the medical activity. St Vincent's Hospital confirmed he was ventilated to assist his breathing at the ground and was on life support when he arrived at the hospital.

Hughes was taken to the hospital in nearby Darlinghurst via ambulance. The air ambulance helicopter was not required to transport Hughes.

Cricket Australia Chief Executive Officer James Sutherland said the match had been abandoned in agreement with both teams as Hughes's welfare took priority.

"Our thoughts and prayers are with Phillip Hughes right now. We are also thinking of his family, teammates and friends in the Australian cricket family," said Sutherland.

"I think everyone knows and understands the way he plays his cricket. He’s fiercely determined and extremely proud of his achievements.

"I guess he’s a quiet achiever, but he has the respect of all of his teammates."

"His welfare is our highest priority. We’re also naturally concerned about all of those involved in today’s game and will be giving them our utmost support."

Australian Cricketers’ Association Chief Executive Officer Alastair Nicholson also sent his support to Hughes.

"We were obviously shocked to learn of the seriousness of the incident involving Phillip. While we have faith that he's receiving the best available treatment, the situation will impact his family, friends, and those directly involved on the field," said Nicholson.

"The ACA is therefore working closely with CA to arrange the appropriate counselling for those affected. Naturally our thoughts are with him and we wish him well from all the ACA members."

Cricket NSW CEO Andrew Jones added: "Players and staff from both South Australia and New South Wales are obviously very concerned for Phillip’s health and, like Phillip, are receiving appropriate support," Jones said.

"Phillip grew up in NSW and is a former Blue and is held in the highest regard by his current and former teammates.

"The thoughts and prayers of all at Cricket NSW and indeed everyone in Australian Cricket are with Phillip the very best for a speedy and full recovery."

Hughes has 26 Test appearances for Australia since making his debut in 2009. A prolific batsman with 26 first-class centuries and an average of 46.18. He was expecting to be fighting for a possible Test berth with uncertainy surrounding the fitness of Clarke and had looked in good touch, compiling a patient half-century before the blow.