NICE, FRANCE (NBC News) - 10:00PM UPDATE:
A truck plowed into pedestrians during Bastille Day celebrations in the popular French seaside city of Nice Thursday, leaving at least 80 people dead in what the nation's president called "obviously a terrorist attack."
The deadly toll, which included several children, came after the truck slammed into revelers gathered on a promenade to watch fireworks, French President Francois Hollande said in an address Friday morning.
"Such a monstrosity," Hollande said. He pledged to step up efforts to fight terror in Iraq and Syria, and extended a state of emergency for three months.
"France is deeply saddened, but it is also very strong," Hollande said. "I can assure you we will always be stronger than the fanatics who are trying to attack us."
The driver was killed by police, Hollande said. It is unknown if anyone else was involved, Hollande said. French media, citing a police source, reported that ID papers belonging to a French-Tunisian were found in the truck. A source told NBC News the driver is believed to have been a French national of Tunisian descent.
The truck struck the crowd at around 10:40 p.m. local time (4:40 p.m. ET) shortly after a fireworks display, officials and witnesses said.
Christian Estrosi, president of the Provence-Alpes-Côte-d'Azur region that includes Nice, told French media that the driver also shot at people. A senior U.S. military official told NBC News that guns and explosives were found in the truck.
A truck plowed into pedestrians during Bastille Day celebrations in the popular French seaside city of Nice Thursday, leaving at least 75 people dead, officials said.
The regional deputy for the Alpes-Maritimes department where Nice is located, Eric Ciotti, told French broadcaster BFM-TV early Friday that 75 people were confirmed dead. Former Nice mayor Christian Estrosi said 77 were dead.
A spokesperson for France's Interior Ministry said on Twitter: "The individual who was driving the truck was neutralized. Investigation will determine if he was acting alone." Police urged residents to stay in their homes.
A truck plowed into a group of pedestrians in Nice, France, Thursday night as people celebrated Bastille Day, authorities said.
The mayor of Nice, Christian Estrosi, said on Twitter there appeared to be dozens of deaths.
The local Nice Martin newspaper reported that a car ran into a crowd watching a 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," witness Andrew Botros, an Edinburgh man who owns a holiday apartment in Nice, told NBC News in a Twitter message. "Some dead. Horrific," Botros said.
Photos and video on social media appeared to show crowds running from the scene, and people several injured on the ground.
Police told NBC they were aware of an incident but were still investigating.
Following the incident, Nice Mayor Christian Estrosi tweeted in french, "Dear nice, the driver of a truck appears to have made dozens of deaths. Stay for the moment to your home. More info to come."
France has been on edge since a series of coordinated terror attacks in Paris in November that left 130 people dead. The terror group ISIS claimed responsibility for that attack.
Bastille Day, also known as National Day, commemorates the storming of the Bastille prison during the French revolution in 1789.