The 25-year-old collapsed after being struck on the side of the head by a Sean Abbott delivery and was stretchered from the ground. He is currently undergoing surgery and according to Ambulance officials he was in a critical condition. Cricket Australia Chief Executive Officer James Sutherland also extended his best wishes to Hughes.
A statement issued by South Australia Cricket Association said, "On behalf of the SACA Board and administration, our thoughts and prayers are with Phil Hughes and his family at this time.
"Phil suffered an injury to his head from a delivery Phil has been taken to hospital in Sydney and has been accompanied by family members and SACA General Manager High Performance, Tim Nielsen."
The South Australia Cricket Association CEO, Keith Bradshaw, spoke briefly to the media, saying he's "very shocked" and "very upset" by the incident.
He said the outcome of Hughes' surgery is unlikely to be known for 24-48 hours.
Cricket Australia CEO, James Sutherland also spoke to reporters.
"To be honest it sends shudders through you a little bit," he said.
"Pleasingly there was medical attention he was able to receive immediately at the ground.
"All we know is that it's serious and he's fortunate to be in the best possible place right now with experts all around him," he said.
Hughes was given CPR on the stretcher as he came off the field, with Australian opener David Warner alongside him.
At least three ambulances and a helicopter were on hand to treat the 25-year-old and transport him to St Vincent's Hospital.
Australian captain Michael Clarke was one of the first people to rush to the hospital and is currently with Hughes's sister and mother Virginia who were at the SCG on Tuesday.
Sutherland said, "Our thoughts and prayers are with Phil Hughes right now. We are also thinking of his family, team mates and friends in the Australian cricket family.
"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 Phil. 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," he said.
"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."
Hughes, who was trying for a Test recall at the India series, had played an innings of 63 runs before collapsing to the ground after being hit by the rising delivery.
Making his Test debut in South Africa in 2009, Hughes scored 75 in the second innings at Johannesburg, before hitting centuries in both innings of the second Test at Durban. He played 26 Tests in his career.
The 25-year-old collapsed after being struck on the side of the head by a Sean Abbott delivery and was stretchered from the ground. He is currently undergoing surgery and according to Ambulance officials he was in a critical condition.
Cricket Australia Chief Executive Officer James Sutherland also extended his best wishes to Hughes.