A truck drove into a crowd celebrating Bastille Day in Nice, France, killing at least 77 people Thursday evening and injuring around 100 more. French President François Hollande said there could be no question the attack was an act of terrorism. 

NPR reported the truck started about a mile away and plowed into a crowd of people watching fireworks on the French national holiday, leaving injured and dead along a stretch of the waterfront. A witness told the Associated Press that after the truck entered the crowd, a driver emerged from the vehicle with a gun, shooting at people. He was shot and killed, NPR reported. 

• The Guardian and New York Times have live updates in English. Le Monde is also updating from the scene. 

This story is no longer being updated.

Witness: 'There was just mad chaos' 

Eighteen-year-old Darryl Curtis was standing by the side of the road during the Bastille Day celebrations in Nice when he saw the truck pull over and he started to hear shooting.

"There was just mad chaos," he told KPCC. He said he was walking to the beach when he heard the truck veer into the crowd.

Curtis, a Baltimore native, said he was in France following Rihanna's world tour before he heads to college this year.

"I was just walking to the beach," he said. "All of a sudden, you just see a gray truck just pull up into the crowd. And all of the sudden people just started getting hit."

Listen to his story here:

Sheriff says attack like Nice has long been feared

The United States Embassy in France issued an emergency message urging U.S. citizens in Nice to contact family members and loved ones. It also says they should avoid the area, exercise caution if they're nearby and monitor media reports for information. The Embassy also said it was working to determine if any U.S. citizens were harmed.

In Los Angeles, city police say they remain vigilant, but aren't on heightened alert. Los Angeles Airport officials say they haven't seen a need yet to boost security.

The Los Angeles County Sheriff's Department will be changing tactics due to the Nice attack, Commander John Stedman told KPCC. He's the head of the department's anti-terrorism unit.

Stedman said the department has been worrying about and planning for vehicle attacks for a long time, but added that large crowds are hard to protect. He said they try to make sure that access roads at events that they're providing security for keep vehicles at slower speeds to avoid attacks like this one. He also said sheriff's deputies put up barriers if there's an opportunity.

"We do the best we can. Sometimes access is hard, because you don't want to ruin the event by being so security conscious, but you do everything you can to make sure that everybody's safe," Stedman said.

Stedman said that an attack like the attack in Nice isn't difficult to pull off.

"Even if it was well planned, it's something that anybody could do, right? Everybody has a car, especially in Los Angeles. Everybody has access. I mean, you could go rent a truck. I mean, this isn't high-tech, and I think that's what's so frightening," Stedman said.

Stedman said that the truck that was used in the Nice attack was larger than what he'd seen discussed before.

"They sort of talked about pickup trucks, but using what appeared to be a large moving van, which, you get that thing up to speed, and it's really hard to stop. Can't take a good shot if you're going to shoot at it, or it's going to take a very large barrier to stop something like that, because it weighs a lot, it gets a lot of momentum going, and those are very hard to stop. Much bigger than I think what they talked about, but unfortunately, it was very effective," Stedman said.

Stedman said that a recent example of the Sheriff Department's shift in tactics came during L.A.'s Pride Parade, which followed on the heels of the nightclub shooting in Orlando.

"We had those events the day before, and immediately increased the number of people that we assigned to the event," Stedman said. "We have good plans, but when there's a real timely event like this, you've got to look at them again and again, right up to the... I mean, we changed that plan hours before the event to make sure that that event was secure — more secure than it was before. And it was pretty secure to begin with."

Stedman said that he'd been talking to incident commanders about events that were planned for Thursday, looking at whether plans needed to be changed.

"We're doing everything we can. I mean, that's the bottom line. We're talking to everyone, sharing everything, and really trying to get our incident commanders to really look at those plans and make sure that they're everything they can be," Stedman said.

Authorities rely on the public to provide information when they see something in order to stop attacks, Stedman said.

"With so much going on in L.A., it's really hard to predict without any reliable, credible information," Stedman said. "Nobody wants to be that person, but boy, I'd hate to have to live with myself if I knew something or I thought something and I didn't report it. That would be rough."

Ultimately, Stedman said that people have to go on and live their lives — while also being prepared.

"I tell my kids, I mean, you can't live in fear. You have to go to the things that you want to do in life. I tell my kids all the time, you always have to have an exit plan. You can go and have a good time, but you always need to know where you're going to go if something happens," Stedman said. "You can't walk around in a cloud, in a bubble. You've got to think about where you're at and what you're doing."

In LA, more shock, frustration, sadness

Nicole Marquis with Alliance Française de Pasadena had just finished celebrating Bastille Day when she heard the news about the incident.  The organization teaches French and holds cultural events. Marquis is from France.

"Honestly, I don't know what to think about it. I just think we live in a crazy world," she told KPCC. "I just saw a message on Facebook from somebody that had an artist that was here a few years ago, who posted that he was fine after," Marquis said.

The Alliance  held a luncheon Thursday to celebrate Bastille Day at Cafe Bizou which 50 people attended.

Greg and Kim Magsayo were headed to Eagle Rock’s Café Beaujolais Thursday to celebrate their 26th anniversary. They developed a taste for French food while on vacation in France. They were shocked and saddened to learn of the latest attack.

“It makes me feel bad because we were just in France, what was it, last year, two years ago?” Greg Magsayo said. “I don’t know what they can do about it. There are just so many bad people.”
 
The restaurant manager declined to be interviewed, he said it was too soon and too sad to describe his and his customers’ reactions to the deaths in Nice.
 
There was a similar story at Café Bizou in Pasadena, where about 50 people with the nearby Alliance Francaise had gone for a Bastille Day celebration. The manager was hosting customers, but did not want to talk about the apparent attack.

This story has been updated.