The Irish Football Association has expressed its sympathy to the family of Ryan McBride.
The 27-year-old Derry City captain was found dead at his home on Sunday evening.
The Irish FA's chief executive, Patrick Nelson, said: “The whole football family on the island of Ireland is shocked by the tragic news of Ryan McBride’s passing. Our thoughts are with his family and with Derry City Football Club, its supporters and staff.”
Tributes have also flooded in from Irish League clubs on Twitter.
Linfield tweeted: "Deepest sympathy to the family of Ryan McBride and to everyone at @derrycityfc on the sudden passing of their club captain."
Ballymena United posted: "We send our heartfelt condolences to the family, friends of Ryan McBride and @derrycityfc after his tragic passing.Thoughts are with you all."
Derry City's neighbours Institute wrote: "Our heartfelt condolences go out to the family & friends of @derrycityfc captain Ryan McBride on the news of his sudden, tragic passing."
"Thoughts and prayers with the family and friends of Ryan McBride and all those at @derrycityfc following tonight's tragic news," added Glenavon FC.
A message posted on Crusaders' Twitter page read: "Sincere condolences to the family of Ryan McBride and also everyone at @derrycityfc on the sudden passing of their club captain."