Update: Authorities Believe Nice Attack Was Planned With Accomplices

Update: Authorities believe that the July 14 attack on Nice, France, that left 84 people dead had been planned for months, The Associated Press reported on Thursday. French prosecutor François Molins said that five people are facing preliminary charges of terrorism for their suspected roles in the attack. Information recovered from the attacker’s phone by the investigation showed searches and photos indicating he had been planning an attack since last year. Update: July 17, 2016, 9:50 a.m.: Two new people have been detained in the investigation into Thursday's deadly attack in Nice, reports The Associated Press. A French official confirmed that authorities had detained a man and woman. The official provided no details on their identities. Meanwhile, the estranged wife of truck driver Mohamed Lahouaiej Bouhlel was released from police custody. On Sunday, France's health minister also confirmed that 85 people remain hospitalized — 18 of them are in life-threatening condition, including a child.

Update: July 16, 2016, 10:44 a.m.:French prosecutors have confirmed that five people suspected to be linked to Thursday night’s attack in Nice, France, are in police custody. The BBC reports that the five included the attacker’s estranged wife. The names of those held have not been released.

Update: July 16, 2016, 8:32 a.m.:A media agency run by the Islamic State group has praised the driver of the truck that plowed through a Bastille Day celebration in Nice, France, on Thursday, killing dozens and wounding hundreds, as a "soldier" who "carried out the operation in response to calls to target the citizens of coalition countries fighting the Islamic State," according to The Associated Press. There is no indication that ISIS was involved in planning the attack ahead of time, The AP notes.

Update: July 15, 2016, 11:30 a.m.: In a press conference on Friday morning, François Molins, the French anti-terror prosecutor, upped the count of those wounded to 202, with 52 people in critical or intensive care. He said that, of the 84 people killed, 10 of them were children. He also clarified that, despite reports of weapons found in the cab of the truck used for the attack, at least three had turned out to be dummies, including two false assault rifles and a false handgun. Molins also gave out more information on the attacker, saying via a translator that the suspect had been “entirely unknown to intelligence services” and had never been the subject of an investigation. He said that authorities had searched two addresses associated with the suspect and seized audio equipment and various documents.

Update: July 15, 2016, 10:05 a.m.: An American father and his 11-year-old son are among those killed in Thursday night’s attack on Nice, France, NBC News reported. A representative of the family confirmed to the network that the victims were Sean Copeland, 51, and his son, Brodie, from Lakeway, TX.

Police identified the attacker as Mohamed Bouhlel, a 31-year-old Nice resident, according to The Associated Press. Officials told the news source that Bouhlel was a petty criminal originally from Tunisia, a former French colony. No group has claimed responsibility for the attack. French President François Hollande said in a press conference on Friday that about 50 people were still “between life and death.” Health officials told French daily newspaper Le Monde that 188 patients were being treated at hospitals around the Alpes-Maritimes region. Officials also asked those who wished to donate blood to wait several days, as there was no urgent need for donations at the moment.

Update: July 14, 2016, 11:58 p.m.: New reports indicate that the death toll is now officially 84, with 18 still seriously injured, according to both the Guardian and BBC. The driver reportedly zig-zagged through the crowd and shot pedestrians as he went an estimated 30 mph for more than a mile. “The city of Nice has been hit by terrorism on the day of our national holiday. Immense pain, the country is in mourning. The French will face it,” tweeted French Prime Minister Manuel Valls. Hillary Clinton also released a statement condemning the attacks.

Update: July 14, 2016, 10:24 p.m.: French President François Hollande gave a press conference condemning the attacks and extending France's state of emergency for three months past its scheduled July 26 end date. Hollande said that the toll of 77 dead included children and that there were still 20 gravely wounded people. "France is badly hit by this tragedy. We are horrified," Hollande said. "But France is strong, and France will always be stronger I assure you." The President also said the attack was "of a terrorist character" and promised to boost French security forces at home and military forces in the Middle East. "France is tearful, sorrowful, but it is strong and will be always more than the zealots who now want to hit her," he said in a tweet following the press conference. Rihanna was reportedly in Nice during the attack, preparing for her Friday concert in the city's Allianz Riviera Stadium. That concert has now been cancelled, though the star was unharmed. The city's long-running jazz festival, scheduled to open Saturday, has also been cancelled.

Update: July 14, 2016, 8:56 p.m.: An official in the regional government placed the official death count at 77, with at least 50 injured, the Guardian reports. The driver reportedly exited the vehicle and exchanged gunfire with police before being shot and killed. Firsthand accounts of the attack are beginning to filter in. "A fraction of a second later, an enormous white truck came along at a crazy speed, turning the wheel to mow down the maximum number of people," Nice Matin journalist Damien Allemand wrote in a Medium post. "I saw bodies flying like bowling pins along its route. Heard noises, cries that I will never forget." President Obama gave a statement and offered his support to France in their ongoing investigation. "On behalf of the American people, I condemn in the strongest terms what appears to be a horrific terrorist attack in Nice, France, which killed and wounded dozens of innocent civilians," Obama said. "Our thoughts and prayers are with the families and other loved ones of those killed, and we wish a full recovery for the many wounded."

Update: July 14, 2016, 7:41 p.m.: The truck drove two kilometers through the Nice crowd, the BBC reports. At least 60 were killed in the attack, and the truck was "loaded with arms and grenades" regional president Christian Estrosi tells the AP.

French Secretary of State Juliette Méadel asked that photos and videos of the attack not be shared on social media out of respect for the victims. Former French President Nicolas Sarkozy expressed his sadness in the wake of the attacks. Newly-minted British Prime Minister Theresa May is being apprised of developments. A spokesperson for the new administration told the BBC, "Our thoughts are with all those affected by this terrible incident on what was a day of national celebration."

Dozens were feared killed or injured when a truck plowed into a crowd celebrating Bastille Day on Thursday in the French city of Nice, the BBC and Yahoo report. The mayor and police urged people to stay indoors via Twitter. "The driver of a van appears to have killed dozens. Stay in your homes for now. More info to follow," mayor Christian Estrosi tweeted. Early reports indicate a chaotic scene, but a French official has already declared that the truck's driver smashed into the crowd as a deliberate attack, the AP reports. The van struck crowds that had gathered on the famous Promenade des Anglais to watch the annual fireworks display. "White truck literally racing through crowds of all ages. People either caught in path or forced to jump onto rocks over beach barrier," eyewitness Andrew Botros told NBC News via Twitter message. "Some dead. Horrific," Botros told NBC. Video showed crowds fleeing.

This is a developing story. Check back for updates.