Titmuss was said to be conscious when he left the session in the ambulance. He was transported to Northern Beaches Hospital but later took a turn for the worse and was transferred to Royal North Shore Hospital, where he died.
Manly chief executive Stephen Humphreys said the club was “in shock” and unaware of any underlying medical conditions that may have contributed to the player’s death.
“We are also without answers about what has happened,” he said. “I wasn’t present when it happened, but I am on my way to the hospital, Des [Hasler, Sea Eagles coach] is there now, so we might find out more then.”
Hasler said the club was “devastated”.
“Keith was a very popular character among the playing group,” he said. “He will be sorely missed but never forgotten by the Sea Eagles.”
Manly informed players who were present at the session, including Daly Cherry-Evans, Jake and Tom Trbojevic, via a meeting on Monday afternoon.
NRL chief executive Andrew Abdo said the game would offer counselling to the club and his teammates.
“This is a tragic day for rugby league,’’ he said.
“The game has lost a promising young player with the world at his feet. Keith had made it into Manly’s Top 30 for the 2021 season after coming through the club’s junior ranks.”
Abdo said the NRL would make sure Titmuss’ family had “every support” they required from the governing body.
“We are one family and today we have lost a member of that family. On behalf of the commission and the game, I send my deepest condolences to Keith’s family.”
Abdo said NRL wellbeing staff were at the club on Monday afternoon and had arranged grief counselling.
Titmuss scored the match-winning try for the Sea Eagles in the 2017 NYC grand final and was named the Manly Jersey Flegg Cup Players’ Player in 2019.
He came through the Sea Eagles junior representative teams as a teenager and had been included in Manly’s senior squad for 2021.
It is not the first time Manly have experienced a serious health incident during pre-season training.
In 2018, forward Lloyd Perrett revealed he suffered a seizure and heatstroke after collapsing at a training session.
Perrett, 23, sparked serious concerns for the club in January of that year after collapsing twice during two-kilometre time trials, due to suspected heat exhaustion.
“I woke up thinking what happened? I’m about to die. I had no understanding of what had gone on,” he told foxsports.com.au.
The young forward was rushed to hospital, and said he thought he “must be dying” upon regaining consciousness.
Earlier this year, the NRL world was left reeling over news Boyd Cordner’s cousin, 19-year-old Joel Dark, had passed away after a head knock in a rugby league game on September 6.
The youngster was playing in his first-grade debut for the Central Newcastle club when the accident occurred. Dark suffered a seizure on the field. More than $100,000 was raised in just five days via a GoFundMe page for the teenager’s family.
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Sarah is a journalist for The Sydney Morning Herald.
Adam Pengilly is a Sports reporter for The Sydney Morning Herald.