"Phil Hughes has been taken to St Vincent's Hospital," said Cricket NSW official Malcolm Conn. "Clearly the priority is Phil's health and we want to keep his family fully  informed. 

"We don't have any update on Phil's health at the moment. 'Doc' Orchard, the NSW doctor on duty has gone with Phil to the hospital and when John is in a position he'll provide a written statement of Phil's condition but until then we can't say anything more because we don't know."

The family of Phil Hughes has released a statement through South Australia Cricket's Tim Neilson.

"Phil Hughes suffered an injury this afternoon. He is presently undergoing surgery and the outcome of that surgery is unlikely to be known for the next 24 to 48 hours.

"In the meantime we would ask, we would really appreciate it, if you would look after the family and the friends and respect their privacy."

Cricket Australia chief executive James Sutherland has released a statement, extending his best wishes to Hughes. 

"We were obviously shocked to learn of the seriousness of the incident involving Phil," he said.

"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. 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."

EARLIER: A spokesman for the Ambulance Service of NSW said paramedics were called to Moore Park at 2.37pm, and Hughes was taken to St Vincents Hospital by ambulance in a critical condition.

Hughes was attempting a pull shot from a delivery by Sean Abbott when he was struck. After the blow, Hughes stood for some time while looking at his feet and then crashed face-first onto the pitch. The NSW players and umpires called for help immediately.

NSW team doctor John Orchard was on the boundary administering assistance as Hughes lay on a stretcher on the medicab. Medical staff were working on Hughes 30 minutes after the delivery struck him and eventually three ambulances arrived on the ground to administer assistance. A helicopter arrived at the ground with another doctor to assist.

Players and ground staff held up a white sheet to screen him from the spectators who were looking on.

Play was suspended immediately with the umpires eventually abandoning play for the day. Hughes' former opening partner David Warner stood by his friend's side, as did Blues skipper Brad Haddin and some South Australian players.

The South Australian opener was breathing through an oxygen mask. 

Hughes was unbeaten on 63 and fighting for a berth in the squad for the first Test next week with the likely exclusion of skipper and No.4 batsman Michael Clarke due to a hamstring injury.

The manner in which the former Test opener collapsed, face-first onto the ground was like watching a boxer who falls from a delayed knockout blow.