Books of condolence have been opened across Northern Ireland for the victims of the twin attacks in Norway.
In Belfast, Lord Mayor Niall O Donnghaile was first to sign the book which will remain open for members of the public at the City Hall.
In Londonderry Mayor Maurice Devenney was among the first to sign the book at the Guildhall.
The Derry book of condolence will remain open throughout this week from 9am to 5pm.
Mr Devenney said: "This is a terrible time for the people of Norway.
"They are numb with shock and emotion and are finding it hard to comprehend the reasoning behind this most tragic act of terror.
"The book of condolence will provide local people with an opportunity to express their sympathy and offer their support to the victims and their families as they try to come to terms with their loss," he added.
Meanwhile SDLP leader Margaret Ritchie also opened a book at her party's headquarters on the Ormeau Road, in south Belfast.
The SDLP is a sister party of the Norwegian Labour Party, whose members were killed at a youth camp on Utoya island.
In Antrim, Mayor Paul Michael said a book of condolence would remain open until August 31.
"My fellow councillors and I have been deeply moved by the extent of this disaster and the suffering it has brought to so many people," he said. "The book of condolence will give our community the opportunity to express their sympathy to the families of all the victims," he added.