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.
A property developer from Belfast has said he and his family avoided the horrific lorry attack in Nice due to his children's decision not to attend the Bastille Day fireworks display.
Suneil Sharma is in Nice with his partner and sons aged 11 and 15 as well as his sister and her family.
He was at a restaurant on the promenade when the lorry driver drove into the crowds on the streets.
“I was at the Negresco on the front of the Promenade des Anglais. We were there for dinner, my children were with their aunt, they were coming to join us literally within half an hour to see the firework display,” he explained.
“We just didn’t know what had happened to be honest with you, we heard the firework display had just finished and we were very fortunate in that our boys had been ordering a pizza and got delayed and decided then not to come down and meet us,” he continued.
“We just didn’t know what was going on, it just happened so suddenly. One minute people were having a great time, celebrating the iconic French holiday of Bastille Day, the next minute it was pandemonium. We were just shocked.
“Within minutes the hotel was locked down, nobody could leave, the police arrived and we were in the hotel for over two and a half hours.”
“Slowly but surely we heard information about the vehicle killing innocent people and families out to celebrate Bastille Day, so it was horrific,” Mr Sharma added.
“We were very lucky because we had planned to be there in front of the hotel, but simply ordering a pizza meant we were lucky we weren’t involved in that.”
Mr Sharma said his thoughts were with the families of the victims.
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”.