Paris - French President Francois Hollande on Thursday promised "truth and transparency" from an inquiry into allegations of lax security the night of the Bastille Day attack in Nice that killed 84 people."When there is a tragedy, or in this case an attack with many dead... there will naturally be questions," Hollande said during a visit to Dublin, adding that the conclusions of the police probe would be announced next week.The third major attack in France in 18 months has left France's Socialist government fending off accusations of failing to protect the nation.Liberation daily reported on Thursday that only one municipal police car was guarding the spot where Mohamed Lahouaiej Bouhlel crashed a 19-ton truck through barriers and into crowds on the promenade.A week after the rampage, five suspects arrested over links to the Tunisian attacker are to appear before anti-terrorism judges who will decide whether to charge them. The attack came just as France was preparing to lift the state of emergency in place since the November attacks in Paris, prompting an immediate reversal of course.On Thursday, parliament finalised adoption of a bill extending the emergency laws for a fourth time, after it was toughened up by the right-dominated Senate.The final version bans gatherings where sufficient security cannot be provided and makes it easier to shut places of worship where preachers incite hate or violence. Since November the authorities have had emergency powers to carry out searches by day or night and place people under house arrest.While France continues to mourn the victims of the assault that took terror to the shores of the Riviera, the government continues to be plagued by questions over possible security failings.Prime Minister Manuel Valls has accused members of the centre-right Republicans party of "lying to the French" after some suggested the attack could have been thwarted.Just hours after he warned the French had to learn to live with terror, the Islamic State (ISIS) group - which claimed the Nice attack - posted a video showing two French-speaking jihadists threatening more attacks against the country. The video appeared to have been shot in Iraq.ISIS last week claimed Bouhlel as one of its "soldiers".Investigators have said they have no proof yet that the driver, who was shot dead by police, had pledged allegiance to the group. Kalashnikov seized In Nice, investigators found a Kalashnikov rifle and a bag of ammunition in the basement of a 22-year-old man who is among five being held over links to Bouhlel.The suspect received text messages from Bouhlel on the night of the attack, in which Bouhlel praised him for providing the pistol he used during a shoot-out with police.About 100 investigators are poring over masses of data linked to the probe.Pictures found on Bouhlel's mobile phone indicate he was studying several locations where crowds gathered as possible targets.One photo concerns a fireworks display on August 15, another a race on January 10 along the Promenade des Anglais where the attack took place, and yet another the opening times of a fan zone during the Euro football tournament. Police interviewed hundreds of people close to Bouhlel, who said he had shown no interest in his Muslim religion until recently.His family and friends have described him as violent and possibly mentally disturbed.Former FBI profiler Mary Ellen O'Toole said the majority of his reported traits were "only seen collectively in someone who is psychopathic"."This is probably one of the most callous crimes you and I have ever heard of, it's very cold-blooded and it's predatory."