Bastille Day attack: What we know so far

(CNN)A truck rammed into a crowd that had gathered Thursday to celebrate Bastille Day in Nice, killing at least 84 people.

The crowd had watched a fireworks show on the promenade and was leaving the area when a large white truck appeared. The driver of the truck fired a gun at people and then plowed through the crowd on the main street for more than a mile. One witness said that the truck appeared to zigzag through the crowd, and another witness said the driver appeared to accelerate when hitting people. The driver was shot and killed by police.
Here's the rundown:

The attack

    What was the scene like? One minute, it was a jubilant celebration of Bastille Day. The next, it devolved into chaos and carnage.
    According to French prosecutor Francois Molins, at about 10:45 p.m. (4:45 p.m. ET), a man in a rented 18-ton refrigerator truck drove along the Promenade des Anglais. He fired on three police officers, who fired back and gave chase. The truck went on about another 300 meters, and police found the driver dead on the passenger's seat.
    Who are the victims? 84 are dead, 10 of which are adolescents. Another 202 people were injured; among those 52 were injured critically.
    At least three children are among those in critical condition, according to Dr. Richelle Christian. Doctors struggled not only to treat the incoming wounded, but to identify them, Christian told CNN. Many children were separated from parents and brought to the hospital.
    Three Germans are among the dead, a Berlin official said. They are two students and one teacher, all female, from the Paula-Fürst-School, Mayor Reinhard Naumann of Berlin's Charlottenburg-Wilmersdorf district said in a statement.
    Americans Sean Copeland and his son, Brodie, of Texas were killed in the attack, a family representative said. The University of California, Berkley says three of its students were among the injured.
    Three Australians, two Chinese and one British national were injured, officials said.

    The investigation

    The driver of the truck has been identified by the French government and anti-terrorism officials as
    Mohamed Lahouaiej Bouhlel, a 31-year-old Tunisian man who lived in Nice. No group has claimed responsibility. The presidents of France and the United States are calling this a terror attack.
    The attacker "is not affiliated with any mosque in Nice," the president of the Union of Mosques in France told CNN on Friday. "Also, as far as we're aware, no one knows him as a practicing Muslim," Mohammed Moussaoui said.
    Bouhlel was "never mean to anyone," a neighbor told CNN. The neighbor says, "He used to come round to her house to help her fix things, like the toilet." Another neighbor said attacker was "very odd" and would not return greetings. "He had a fixed gaze. The children would say hello, he wouldn't say hello. He would only like nod his head. He was very odd. ... I saw him like four times a day."
    The truck and its contents: The truck used in the attack was rented on Monday and was supposed to have been returned Wednesday, Molins said. After the attack, police found in the trailer a bicycle and eight empty pallets. In the cabin, other than the attacker's body, police found a handgun, some ammunition, and a replica handgun and two replica assault rifles, Molins said. In addition, police found a cell phone and various documents.
    Trucks have been used as weapons before, but the lethality of such attacks had been relatively low until the attack in Nice. Not only do we have to worry about truck bombs, now the vehicles are used as weapons, writes Peter Bergen, CNN's national security analyst.

    The response

    French president extends state of emergency: French President François Hollande vowed to crack down on France's enemies and is asking parliament to extend the country's state of emergency by three months. "France is afflicted, but she is strong, and she will always be stronger than the fanatics who want to strike her today," he said.
    World leaders express shock and sympathy: It feels almost routine now. Another terror attack results in an outpouring of condemnation against the attacker and expressions of solidarity for the victims.
    What's the reaction in the U.S.? Presidential candidates Donald Trump and Hillary Clinton chimed in on the France terror attack. "We have to be tough," Trump said, reiterating that the United States should reverse its decision to allow Syrian refugees into the country. Clinton told CNN that greater intelligence gathering, not military force, is necessary. Former House Speaker Newt Gingrich wants the United States to test and deport every person with a Muslim background who believes in Sharia law.
    The Department of Homeland Security says it is increasing security in ways that are both visible and not visible.
    New York stepped up security at high-profile locations including airports, bridges, tunnels and mass transit systems, said Gov. Andrew Cuomo.