At least 84 people have been killed - several of them children - after a lorry driver ploughed into crowds celebrating France's national Bastille Day in Nice.
French President Francois Hollande has described the attack as a "terrorist crime".
Northern Ireland tourists in the popular holiday destination in the south of France have described the chaos and confusion as the attack unfolded.
Belfast City Hall has been bathed in the colours of the French flag in tribute to those killed in Nice.
Politicians across Northern Ireland have expressed their condolences to the many people killed in the terror attack.
Belfast's Lord Mayor and deputy Lord Mayor have opened a book of condolence for those killed in last week's lorry attack in Nice, France.
The Irish Department of Foreign Affairs is "urgently following up" on concerns for the safety of Irish citizens in Nice.
UTV journalist and producer Ben Terry, who was in Nice at the time of the attacks, has described a scene of “mass panic”.