Derry City FC captain Ryan McBride has died, the Irish Football Association has said.
The 27-year-old's cause of death is not yet known.
The Irish FA tweeted: "Thoughts tonight with the family of Ryan McBride and everyone involved with @derrycityfc."
His death comes a day after McBride led his team to a 4-0 victory over Drogheda United.
Drogheda United said on Twitter that they would "would like to offer our deepest condolences to @derrycityfc on the sudden passing of their captain Ryan McBride."
Derry City chairman Phil O'Doherty told the BBC the defender was "an ideal captain" and "a leader on and off the field."
"This news is so hard to take in," O'Doherty said. "He started the season so well and scored a really important goal against Shamrock Rovers recently.
"The players and management staff are in shock and it's an extremely tough time for everyone.
"He was incredibly respected. He was an ideal captain.
"He was from the Brandywell area and he just walked across the road to his home after every game."
- Official Irish FA (@OfficialIrishFA) March 19, 2017
Derry manager Kenny Shiels is quoted by the Irish Times as saying: "Ryan's a player we feel is not only the captain of the team but is influential and leads by example."
The club later added, in a statement on their official Facebook page: "Derry City Football Club is deeply saddened by the untimely death of our captain, Ryan McBride. Our prayers and thoughts are with his father, Lexie, his sisters Colleen, Siuinin and Caitlain, and his partner Mairead who are heartbroken at his loss. We are also conscious of his teammates and our management and support staff. Ryan was a player and a great captain but he was also their friend and teammate. They are deeply shocked and will miss his inspiration and his leadership.
"Our supporters are also shocked and saddened. To them, Ryan was Derry City through and through. The commitment and passion he brought on to the field is the bond that binds player and supporter.
"In the hearts and minds of all of us and long into the future Ryan McBride will be remembered as one of the greats of Derry City Football Club.
"We are also conscious that this is the anniversary of the death of the members of the McGrotty and Daniels family in Buncrana and it is only a short time since we remembered Mark Farren's death.
"It is at times like this that we are reminded that our Club is also a community of people. As in the past, that community will come together to comfort and support Ryan's family.
"In the coming days and weeks we will grieve the loss of our captain and our friend. Sometime in the future, when we have got past the initial shock and have had the proper space to grieve his loss, we will find a way to celebrate his life. We will remember his civility and humility off the field, his commitment and passion on it and the deep love he carried in his heart for Derry City Football Club."