A post from owner Bobby Kasanga on their website said: "We write with heavy hearts and a profound sense of shock after a deeply distressing incident involving our beloved club player Brighton Tutalamo.
"During a routine training session last night, Brighton suffered a sudden heart attack that left him unresponsive and not breathing for a harrowing moment.
— Hackney Wick FC (@HackneyWickFC) November 3, 2023
"It is with immense gratitude that we can report that the quick and heroic actions of our coaching staff came to the fore. With courage and skill, they administered CPR and utilised a defibrillator, ultimately saving Brighton's life.
"As we pen this statement, Brighton is under the care of medical professionals and remains in an induced coma.
"The entire Hackney Wick FC family, including our players and staff who bore witness to this traumatic event, are shaken to the core.
"Our thoughts and prayers are with Brighton and his family during this incredibly difficult time.
"We understand that players may be deeply affected by this situation, and we want to assure you that we will keep you updated with any further information as it becomes available.
"Brighton's recovery is our top priority, and we are doing everything within our power to support him and his family.
"To Brighton, we send our sincerest wishes for a speedy and complete recovery. Your strength and resilience are an inspiration to us all. We will stand by your side, every step of the way."
Tutalamo had made 10 appearances so far this season, with Hackney Wick due to visit Thurlow Nunn League Division One South rivals Barkingside on Saturday.
They ran out 6-1 winners over Hoddesdon at Witham Town's Spa Road ground last weekend, with Victory Akam scoring twice and Leonardo Pola Lopete, Frankie Hanmore, Darren Esuka and Kimani McDonald also on target.