The U2 frontman, 56, was dining on the sea front with celebrity chef Alain Ducasse when Mohamed Lahouaiej Bouhlel drove a truck through crowds celebrating Bastille Day.
The owner of the restaurant told Le Perisien: “There was a panic, because some people who ran collapsed in front of the terrace. All guests are brought indoors and we closed the doors.”
A fellow diner said: “After half an hour, the police evacuated us. Everyone came out onto Place Massena, under police protection. Bono and his friends, like the other people, left the restaurant with hands on head.”
U2 tweeted after the atrocity.
Tourists have returned to the promenade in Nice where scores of people were mown down in a lorry attack as it reopened amid the news France is to call up thousands of reserve forces to boost security.
The Promenade des Anglais reopened around 36 hours after Thursday’s attack which saw 84 people killed and more than 200 injured after a lorry was driven through throngs of revellers celebrating Bastille Day.
Holidaymakers walked along the waterside stretch on Saturday, which is lined with hotels and restaurants, while police officers kept watch.
Flowers, cards and messages of solidarity marked the spots where bodies had been left strewn on the road in the aftermath of the massacre.
Candles burned late into the night as crowds gathered once again in memory of those killed and injured.
The Islamic State group has claimed lorry driver Mohamed Lahouaiej Bouhlel was “a soldier” acting on its behalf by committing the murders.
The IS claim of responsibility came after the French authorities said Bouhlel had no known links with terrorists, unlike those behind previous attacks in Paris.
And a former neighbour said the 31 year old had never spoken about extremism.
Bouhlel drove a 19-tonne hired lorry at speed into masses of people before he was shot dead by police.
Speaking outside the high-rise block of flats on Boulevard Henri Sappia, where the suspect had previously lived with his family, Samiq, 19, who did not want to give his surname, said: “I never heard him speak about extremism, I cannot believe that he was a member of Islamic State.”
He said people thought Bouhlel had psychological problems.
“He was a little bit crazy,” he said, but he added that he was shocked by what had happened.
The apartment on Route de Turin where Bouhlel was believed to be living before the attack was raided by police, and a view through the keyhole showed items including what appeared to be boxes of medication and a strip of tablets.
The driver’s father has said that Bouhlel had received psychiatric treatment in the past.
A neighbour and her young daughter said he lived a reclusive life, failing to respond when they said hello.
Interior minister Bernard Cazeneuve, who announced 12,000 extra police reserves are being called up alongside the 120,000 police and soldiers already in place across the country, said Bouhlel appeared to have been radicalised only recently.
According to reports, his ex-wife was also being questioned.
The woman who was estranged from him and had been subject to his domestic violence, was taken into custody for her own protection, French media reported.
Five people have been arrested since the attack.
Many people are still awaiting news of their loved ones either injured in hospital or missing since the attack.
One man lost six members of his family, French media reported.
An eyewitness said she saw people hanging on to the lorry in a desperate bid to stop the killing spree.
Tita Siren, from Finland, was on holiday in the city and witnessed events from a hotel terrace.
She said: “I recognised that one or two men were trying to open the door of the driver. They were hanging on the door so trying to save other people’s lives.”
She added: “The whole width of the truck was full of people in front of it and it just drove over the people and they fell, like the driver was bowling.”