Martin McGuinness, the former deputy first minister in Northern Ireland and former IRA commander, has died at the age of 66.
The cause has been reported to be a rare heart condition, with which he was diagnosed at the end of 2016.
He passed away surrounded by his family members in his hometown of Londonderry.
His former party, Sinn Fein, confirmed the news this morning, saying: "It is with deep regret and sadness that we have learnt of the death of our friend and comrade Martin McGuinness who passed away in Derry during the night.
"He will be sorely missed by all who knew him."
The party president Gerry Adams paid tribute, saying: "Throughout his life, Martin showed great determination, dignity and humility. It was no different during his short illness.
"He was a passionate republican who worked tirelessly for peace and reconciliation and for the reunification of his country.
"But above all he loved his family and the people of Derry and was immensely proud of both."
Lord Hain, the former Northern Ireland secretary, told the BBC McGuinness was key to acheiving peace in Northern Ireland.
He told Radio 4: "He had the grassroots credibility which could enable him to take his followers from the past of terror and horror into a democratic future, which is what he did.
"Sometimes in the history of conflicts, you need leaders who can rise above their past. Martin McGuinness certainly stood the test and proved to be an indispensable figure."