NICE, France, July 14 (UPI) -- At least 84 people celebrating Bastille Day in southeast France were killed and injured Thursday when a truck crashed into a crowd in the town of Nice, apparently on purpose, authorities said.
A large number of people were present at the nighttime celebrations, which included fireworks on the city's famous promenade. Bastille Day, known locally as La fête nationale, is the French national holiday that commemorates the 1789 Battle of Bastille during the French Revolution.
Some witnesses reported hearing gunfire, as well, as the box-type commercial truck ran people over.
"We were enjoying the celebrations when we suddenly saw people running everywhere and tables being pushed down by the movement of panic," teenage witness Daphne Burandé said. "I thought it was a false alert. But then, people were still running."
ABC News reported that the scene included several police officers standing around the truck, which was riddled with bullet holes.
Nice's former mayor, Christian Estrosi, told French media that the driver of the truck fired a weapon as he drove, and that police officers exchanged fire with him and killed him. He also said "the truck was loaded with arms, loaded with grenades."
French President Francois Hollande vowed to increase security measures in multiple ways, telling reporters "France is afflicted, but she is strong, and she will always be stronger than the fanatics who want to strike her today."
Hollande continued, "I have decided to first maintain a high level of police forces, with 10,000 military staff, as well as our police forces. I have also decided to ask military volunteers to join and help our police forces.
"I have decided that the state of emergency which was supposed to end on July 26 will be extended by three months," he said.
"Nothing will lead us to give in to our will to fight against terrorism. We are going to strengthen our efforts in Syria and Iraq against those who are attacking us on our very soil," Holland said.
France has been on terrorism alert for months since 130 people were killed in an attack in November. French authorities have said for weeks that another terrorist event in the country is likely. Officials were planning to remove that alert at the end of July.
Another horrific attack, this time in Nice, France. Many dead and injured. When will we learn? It is only getting worse.— Donald J. Trump (@realDonaldTrump) July 14, 2016
In the United States, National Security Council spokesman Ned Price said President Barack Obama had been informed of the attack.
"The president has been apprised of the situation in Nice, France, and his national security team will update him, as appropriate," he said.
Thursday evening, Obama issued a statement on the attack.
"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" he 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."
"I have directed my team to be in touch with French officials, and we have offered any assistance that they may need to investigate this attack and bring those responsible to justice," Obama continued. "We stand in solidarity and partnership with France, our oldest ally, as they respond to and recover from this attack.
"On this Bastille Day, 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."
Republican presidential candidate Donald Trump announced on Twitter Thursday that his scheduled announcement of a vice presidential candidate, which was set for Friday, was being postponed due to the event in Nice.