Another terrorist attack hit France as a truck plowed into a crowd watching Bastille Day festivities in Nice on Thursday, killing at least 84 people and injuring 50 others, French officials say.

French authorities are still gathering information about the horrific incident. Multiple witnesses and officials described the chaotic scene in detail as people were celebrating the festive holiday in French Riviera.

Here's what we know at the moment:

WHAT TOOK PLACE?

A truck unexpectedly smashed through bystanders near the iconic Promenade des Anglais in Nice. People were observing Bastille Day: the anniversary of a mob storming a looming fortress that held political prisoners two days after the French Revolution in Paris started in 1789.

Video footage showed men and women — one or two pushing strollers — racing to get away from the promenade with broken bodies splayed out on the asphalt, some of them piled near one another, others bleeding out onto the roadway or twisted into unnatural shapes.

Word of the incident trickled out on social media after Nice Mayor Christian Estrosi sent a tweet that translated to, "Dear Nice residents, the driver of a truck seems to have killed dozens. Stay in your homes for now."

Witnesses described the horrific scene in gruesome detail.

"The driver was obviously determined to crash — the truck drove onto the pavement eight feet from where we were standing," a witness told a newspaper in Nice-Matin. "I saw people fall, a small child on the ground."

"Thank God we decided not to take the young ones" to see the Bastille Day fireworks, witness Yves Lamorelle told USA TODAY. "I am the only one who went. It was completely crazy, the crowd panicked and everyone was trying to flee."