Cricket Australia CEO James Sutherland speaks to the media at the Sydney Cricket Ground where the Australian team gathered following the death of Australian batsman Phillip Hughes, in Sydney on Friday.  The cricket world was plunged into mourning when the talented left-hander died after being knocked unconscious by a ball in a domestic Sheffield Shield game in Sydney this week.

AFP/Sydney

Flags flew at half-mast and thousands of fans and players paid tribute on Friday as Australia and the world cricket community united in an outpouring of grief for the tragic death of batsman Phillip Hughes.

Cricketers the world over paused to remember the player, and a spontaneous #putyourbatsout campaign received a massive response with thousands posting pictures of bats on Twitter.

Australia's stunned Test team comforted each other in a grief counselling session at the Sydney Cricket Ground, where Hughes was knocked unconscious while batting in a domestic game on Tuesday.

The 25-year-old died two days later on Thursday from massive bleeding in his brain, becoming one of the highest profile deaths in sport since Formula One icon Ayrton Senna in 1994.

Shock at the freak accident pulsed around the globe as Hughes featured on front pages worldwide and flags were at half-mast at Lord's, the home of cricket in London.

New South Wales authorities announced a public memorial service for Hughes, while next week's first Test against India hung in the balance.

Four players in Australia's Test squad - David Warner, Brad Haddin, Shane Watson and Nathan Lyon - were on the field when he collapsed after being hit by a Sean Abbott delivery.

"Six or seven days is not a long time, but right now with where we all are, it seems like a million miles away," said Cricket Australia chief executive James Sutherland, referring to next week's game in Brisbane.

Sutherland said the "understanding and empathy" of India's powerful Board of Control for Cricket has been "absolutely outstanding".

"They understand that these are unique and extraordinary circumstances," he said, adding: "We all love cricket and no one loved cricket more than Phillip.

"Cricket will go on and it will go on when we're ready."

Both the Sydney Cricket Ground and the cavernous Melbourne Cricket Ground lowered their flags to half-mast, while club teams from Australia to India paused in a minute's silence.

Before play in the third Test against Pakistan, New Zealand's players lined up their bats and caps outside their dressing room in sombre tribute.

Both teams in Sharjah, who cancelled play on Thursday in shock at the news, also held a minute's silence and donned black armbands.

Rank-and-file fans and superstars alike contributed to #putoutyourbats, posting pictures of bats leaning against front doors, stadiums and statues.

Previously anonymous Sydneysider Paul D. Taylor, who started the campaign, said he was "amazed and humbled by the outcome".

Google Australia joined the trend, decorating its home page with the poignant image of a single bat.

The tragedy transcended sports. Golf number one Rory McIlroy wore a black ribbon as he played the Australian Open in Sydney, and tennis star Rafael Nadal offered his condolences.

Fans of Western Sydney Wanderers planned a minute's applause at 63 minutes - Hughes' score when he was struck down - during Saturday's derby match against Sydney FC.

Australia's rugby team will wear black armbands when they play England at Twickenham on Saturday, and a message of sympathy came from New Zealand's All Blacks.

Meanwhile support remained for Abbott, 22, the unlucky fast bowler who delivered the fateful ball and who was said to be "broken" by the incident.

"That lad is absolutely shaken and broken at the moment," former Test quick Jason Gillespie told Fox Sports.

Doctors said the ball cannoned into the base of Hughes' skull, splitting his vertebral artery and causing massive bleeding in his brain.

Hughes, who was struck below his helmet, remained standing for a few seconds after the blow, before crashing to the pitch face-first.

Experts called it a freak injury with only 100 cases ever reported, and only one known incident as a result of a cricket ball.