A firefighter and father-of-two who died after collapsing on duty following a fire in Co Armagh has been described as a "kind and good natured man" who loved his job.
Nial Hamilton (44) died after dealing with a car fire in the Kilwilkee Estate, Lurgan on Monday night.
The father-of-two collapsed at the scene shortly after the blaze was brought under control before 10pm.
Colleagues gave immediate first aid before an ambulance crew arrived.
He was taken to Craigavon Area Hospital but despite attempts to save him, he was pronounced dead.
The Northern Ireland Fire and Rescue Service (NIFRS) has said "an investigation into the circumstances surrounding the sudden death of our colleague is underway".
Nial Hamilton joined the fire service back in 1990, and had initially served in Cadogan and Knock Fire Stations in Belfast before moving to Lurgan.
NIFRS chief executive Jim Wallace sent condolences on behalf of everyone at the fire service.
"We send our deepest condolences and sympathy to Nial’s wife and sons, his family, friends and colleagues at this very sad time," he said.
"Northern Ireland Fire & Rescue Service is a very close knit organisation and today we are all feeling the pain and loss of Nial’s death.
"We have offered his family our full support at this very difficult time."
The fire service flag is now being flown at half-mast across Northern Ireland, with a minute's silence also being held at headquarters earlier on Tuesday morning.
Mr Hamilton's area commander, John Denvir, described the Co Fermanagh man as a "very popular member" of the team with a very promising career ahead of him.
"Our thoughts are with his wife and sons, his family circle and his many friends and colleagues. Nial was a dedicated firefighter, a very popular member of our team and he had a very promising career ahead of him," he said.
"He will be greatly missed by everyone who knew him."
SDLP MLA Dolores Kelly said Mr Hamilton had been described by colleagues as a "kind and good natured man" who loved his job.
"This was a tragic death of an officer on duty which will be investigated by the appropriate authorities in due course," she said.
"Our thoughts and condolences are with his family, friends and colleagues at this difficult time.
"It is absolutely heart breaking to hear a man who was so well respected and liked by his colleagues has passed away so suddenly. From what his colleagues have said he was extremely good natured and very dedicated to a job that he loved."
Health Minister Edwin Poots said he was saddened to hear of the "tragic death".
"The NI Ambulance Service responded promptly to this emergency and the paramedics are to be commended for their work to treat the firefighter at the scene.
"I understand that Fire Service colleagues also gave emergency first aid in an effort to save him.
"Our firefighters are highly committed, doing an extremely difficult job. We are all very grateful for the fearless work that they do on a daily basis."
Deputy First Minister Martin McGuinness also paid tribute to the firefighter.
Posting on Twitter he said.:
"Very saddened to hear of the death of one our Firefighters in Lurgan last night. My deepest sympathy are with his family, friends & colleagues."
His Sinn Fein colleague John O'Dowd said the death was a "tragic loss to all".