Boomtown Rats guitarist Garry Roberts has died age 72, the band have confirmed.
In the announcement, the band described Garry as "the guy who summed up the sense of who The Rats are".
A statement from the band, posted on their official Facebook page, read: "It is with a very heavy heart that the members of Boomtown Rats announce the death this morning of Garry Roberts", describing him as an "old friend and great guitarist".
"The remaining members of the band, Pete, Bob and Simon, Darren and Al extend their deepest sympathy to his family and friends.
"On a clear spring evening in 1975, in a pub in Dun Laoghaire, Co Dublin, Garry became THE founding member of what turned out to be a great rock 'n' roll band, driven largely by that sound of his.
"A storm of massive considered noise that punched out from his overtaxed amplifiers and which animated not just the rest of the group but audiences he played to around the world.
"For fans he was The Legend – and he was. For us he was Gazzer, the guy who summed up the sense of who The Rats are.
"We have known Garry since we were children and so we feel strangely adrift without him tonight. Safe travels Gaz. Thanks for everything mate."
The statement was then signed by band members Bob, bassist Pete Briquette and drummer Simon Crowe – as well as Darren Beale and Alan Dunne.
Fans shared messages of condolence in the comments section as one wrote: "So sorry to hear this news. Condolences to family, friends and the band".
Another added: "RIP Garry, a big part of the Rats special sound, condolences to family band and other friends. Sad loss."
"Shocking news… Garry… such a gent and a great guitarist Farewell…" a third penned.
And a fourth wrote: "Lost for words, genuinely shocked. Thank you for all the gigs and great tunes. RIP and sincere conduit his loved ones xx".
The guitarist was one of the founding members of the group and is said to have been "instrumental" in choosing the name Boomtown Rats.
As well as playing guitar for the band, Garry contributed backing vocals on most of the recordings – while also playing bass guitar and saxophone on some songs.
Roberts and the rest of the members formed the band in Dublin in 1975.
After the group disbanded in 1986, Roberts went on to work with Simply Red and Orchestral Manoeuvres in t'Dark.
Garry also worked as a sound engineer for Flesh For Lulu on their three-month US Boot Lounge tour in 1987.
Later, he reunited with Bob Geldof as he played guitar on some of his solo tracks.
A biography for the guitarist on the band's official site states: "Garry has never been and never will be an "ex-Boomtown Rat" and he is currently trying to muster enough votes for his nomination as Lord Mayor of Boomtown."