An overnight fire which destroyed the historic Steeple House in Antrim was started deliberately, the NI Fire and Rescue Service has said.
The listed building - formerly the home of Antrim Borough Council - was gutted by the blaze, which was reported at around 5:20am.
The property, built in the 1830s, had been lying vacant for several years, but had been earmarked for possible regeneration.
Expressing his sadness at the loss of the building, the mayor of Antrim and Newtownabbey, Alderman John Smyth, said: "As both mayor of Antrim and Newtownabbey and as a resident of the nearby Steeple area, I’ve always been very proud of this building. As a serving councillor of the legacy Antrim Borough Council, I have fond memories of many council meetings held in the chamber and offices there.
"This is a sad day and a great loss of an historic building and well known Antrim landmark."
South Antrim MP Paul Girvan said he was "very sad" to hear about the fire.
"The centuries-old listed building served as the council offices for Antrim Council for many years and there will be countless fond memories of this building for the people of Antrim," he said.
Ulster Unionist MLA Steve Aiken OBE commented: “I was shocked to hear of this fire and see the aftermath. The building has a long history within the Steeple and Antrim area and to see it in the state it is in after this major fire is clearly upsetting for many local people. I, along with my colleagues, pay tribute to NI Fire and Rescue Service for the manner in which they tackled this blaze.
“The Ulster Unionist Party want to see a full investigation into the fire to establish how it happened and encourage anyone who can assist in establishing the facts to come forward at once.”
Councillor Leah Smyth said it was "distressing" to see the building in ruins, while Councillor Jim Montgomery said it was "stomach churning to see the building in such a sorry state."
DUP Cllr Paul Dunlop commented: " I visited Steeple House to see to see first hand the destruction caused by the overnight arson attack . I met and thanked NIFRS. These attacks do nothing for the community and must be condemned . Please give any information you have to the PSNI."
South Antrim MLA Pam Cameron added: "The sight of Steeple House in flames is one that will bring a sense of sadness to all local people who cherish this historic local building. For many they will have memories of this place in its former glory, and to see it now all but a shell is truly devastating.
"I commend the emergency services for their endeavours in trying to save as much of the building as possible. Once again we are in their debt.
"Obviously any investigation that follows must be thorough and I would encourage anyone with information to pass it to the PSNI.”
A spokesperson for the NI Fire and Rescue Service said two crews from Antrim, one from Ballymena and one from Springfield Road in Belfast battled the overnight blaze.
"Firefighters responded to a call and attended a fire at Steeple House in Antrim. Firefighters were mobilised and using breathing apparatus worked to put out the fire.
"The incident was dealt with at 12:15pm and the cause is determined as deliberate," a NIFRS spokesperson said.