A driver killed 84 people and injured more than 100 others when he steered his speeding truck into a crowd in Nice Thursday night at a celebration of Bastille Day, France's independence holiday.
Ten children are believed to be among those killed while celebrating the holiday on a street closed to traffic at the time along the French Riviera.
French President Francois Hollande addressed the nation Friday, saying that "around 50 are in a critical condition between life and death," after visiting a hospital in the French Riviera city.
U.S. State Department has confirmed that two Americans were killed in the attacks.
Government officials in Nice said many police officers were among the dead. At least 18 of the survivors were said to be in critical condition.
The dead attacker has been identified by police as a 31-year-old French-Tunisian who lived in Nice. He was known to local police for violent delinquent charges, but was not suspected of any extremist or terrorist affiliations by national security agencies.
Hollande said earlier the attack has all the elements of a terrorist attack.
"Nothing will make us give way in the fight against terrorism." He cited the attacks in Paris last November, saying all of France is under the threat of Islamic State. “France as a whole is under the threat of Islamic terrorism. We have to demonstrate absolute vigilance and show determination that is unfailing.”
The French leader met with security officials in the Elysee palace to consider what to do next. Prime Minister Valls addressed the public outside the palace, announcing that the country will observe three days of national mourning following the attacks.
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Hollande said France's state of emergency, set to end later this month, will be extended another three months. He has also enacted the Operation Sentinel, introduced after terror attacks in January 2015 that allow 10,000 extra military personnel to boost the ranks of security forces across the country. He said France will strengthen its roles in Syria and Iraq.
France's Interior Ministry put the death toll at 84 and said the driver was "neutralized," meaning he was shot to death by police. Officers later found the truck had been carrying explosives, grenades and other weapons.
French news reports said the Paris prosecutor's office, which handles major terrorism cases, had been put in charge of the investigation. Nice, France's fifth-largest city and the capital of the Cote d'Azur region, was put on lockdown by security forces in case further attacks might be planned.
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“I went to bed and started to hear people screaming and I saw people running, running, running, police, people crying, people screaming," said VOA producer Linda Ringe who was staying in a hotel overlooking the Promenade des Anglais where the attack took place. “We went downstairs and crossed the street and there were many many bodies and we knew they were dead because they were covered with sheets. Many people were trying to tend to those wounded but so many were dead. People were crying and screaming."
She said the truck continued through the promenade, which is a pedestrian street, until the driver was killed by police.
Ringe said at 7 a.m., hours after the attack, she could still see several bodies covered with sheets from her window.
U.S. President Barack Obama condemned the "horrific terrorist attack" and the slaughter of innocent civilians, and he directed U.S. officials to offer all assistance possible to French authorities.
"On this Bastille Day," the U.S. leader added, "we are reminded of the extraordinary resilience and democratic values that have made France an inspiration to the entire world, and we know that the character of the French Republic will endure long after this devastating and tragic loss of life."
Secretary of State John Kerry said the U.S. embassy in Paris was working to account for the welfare of U.S. citizens in Nice. The American consulate in Marseille said it was trying to "determine if any U.S. citizens were injured in the event."
U.S. Democratic presidential candidate Hillary Clinton said the attack made her "sick at heart." Her Republican opponent, Donald Trump, called the attack "horrible" and said he was postponing plans to announce his vice presidential running mate on Friday.
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