After Nice attack, French officials warn that terror threats will stalk for 'a long time'

France was reminded Friday that terror threats will likely shadow the nation for years to come, as investigators picked through the chaos of the latest attack that left at least 84 people dead when a truck carved a mile-long path of horror through Bastille Day revelers on the French Riviera.

Counterterrorism authorities worked frantically to determine whether the attack had been perpetrated by a lone assailant, or whether it had connections and a support network that could be plotting further violence.

The driver - who zigzagged the 19-ton truck through the crowds, witnesses said - then opened fire on survivors before being shot dead by police. French President Franois Hollande said at least 50 people remained in critical condition, hanging between "life and death."

Two Americans are among the dead, says State Department spokesman John Kirby. The Austin American Statesman identifies them as Texas residents Sean Copeland, 51, and his son Brodie, 11, who were there vacationing.

The driver of the truck was reported Friday by French media to be a 31-year-old local man, a dual French-Tunisian citizen named Mohamed Lahouaiej-Bouhlel.

He lived in Nice and had been in trouble with the police in the past for petty crime, but he was not on the watch list of radicalised young men.

The French newspaper Le Monde said he had recently been charged for a fight after a traffic dispute. In the truck, Le Monde said, police found a plastic pistol, two plastic rifles and an “inactive” grenade.

Prime Minister Manuel Valls said the attack had struck France "in its soul on 14 July, our national day."

Valls said Friday that he believed that terrorism would plague France for the foreseeable future.

"The threat of terrorism, as we have now been saying for a long time, is weighing heavily on France, and it will continue to do so for a long time yet," Valls said after an emergency meeting in Paris. "We are facing a war waged on us by terrorism."

France had just exhaled after living for weeks with terrorism fears during the European soccer championships, which concluded on Sunday, and hours before the violence, Hollande had announced that he planned to allow a state of emergency to expire at the end of the month. On Friday, Hollande announced it would be extended three months instead.

The reverberations spread across Europe. Germany said it would tighten border checks, Italy ordered police officials to reinforce security at all "sensitive targets" and Belgium added additional counterterror measures before its own national holiday celebrations next week.

‘This is DIY terrorism’

There was no immediate claim of responsibility for the Thursday night attack from the Islamic State or other extremist groups. But Islamic State supporters were celebrating the attack on social media.

Police were reported by French media to be investigating whether the driver had acted alone, or with accomplices.

The attack may be the lowest tech, easiest entry point mass killing in recent history. And that’s cause for concern.

As Magnus Ranstorp, an international terror expert at the Swedish Defense College noted, “No training has to go into an attack like this. You get into the truck and turn the ignition and you’re armed and deadly. This is DIY terrorism, Do It Yourself terrorism.”

Nice has been on high terror alert since February. A local government official of the Alp-Maritimes region recently noted that security officials were prepared for nuclear, chemical and bacteria weapons, and were rigorously checking ships in the harbor; attacks from the sea were of particular concern, he said.

There was no mention of trucks.

Revelers running for their lives

Nice prosecutor Jean-Michel Pretre described a horrific scene, with bodies strewn along the roadway, and Sylvie Toffin, a press officer with the local prefecture, said the truck ran over people on a “long trip” down the sidewalk near Nice’s Palais de la Mediterranee, a building that fronts the beach.

Wassim Bouhlel, a Nice native, said that he saw a truck drive into the crowd. “There was carnage on the road,” he said. “Bodies everywhere.” He said the driver emerged with a gun and started shooting.

The Paris prosecutor’s office announced an investigation for “murder, attempted murder in an organized group linked to a terrorist enterprise.”

“We are in a war with terrorists who want to strike us at any price and in a very violent way,” said France’s Interior Minister Bernard Cazeneuve.

The ranking politician of the Alpes-Maritime department that includes Nice said the truck plowed into the crowd over a distance of 1.2 miles. Many of those on the ground were in shorts and other summer clothing.

Eric Ciotti said on BFM TV that police killed the driver “apparently after an exchange of gunfire.”

According to the New York Times, a French lawmaker said a person “with extraordinary courage” jumped onto the front of the vehicle to try to stop it. The driver tried to shoot the person with a pistol and fired on police officers. The police then moved in and killed the man, reported the Times, quoting a story on Europe 1 radio.

Images being broadcast across French media showed revelers running for their lives down Nice’s palm tree-lined Promenade des Anglais, the famous seaside boulevard named for the English aristocrats who proposed its construction in the 19th century.

Video footage showed men and women – one or two pushing strollers – racing to get away from the scenes. And, in what appeared to be evidence of a gun battle, photos showed a truck with at least half a dozen bullet holes punched through its windshield.

‘Help my mother, please!’

President Barack Obama condemned what he said “appears to be a horrific terrorist attack.”

European Council president Donald Tusk said it was a “tragic paradox” that the victims of the attack in Nice were celebrating “liberty, equality and fraternity” – France’s motto – on the country’s national day.

Writing online, Nice Matin journalist Damien Allemand who was at the waterside said the fireworks display had finished and the crowd had got up to leave when they heard a noise and cries.

“A fraction of a second later, an enormous white truck came along at a crazy speed, turning the wheel to mow down the maximum number of people,” he said.

“I saw bodies flying like bowling pins along its route. Heard noises, cries that I will never forget.”

Graphic footage showed a scene of horror up and down 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.

“Help my mother, please!” one person yells out amid a cacophony of screaming and crying. A pink girl’s bicycle is briefly seen overturned by the side of the road.

The origin and authenticity of the footage could not immediately be verified.

Kayla Repan, of Boca Raton, Florida, was among the hundreds gathered on the promenade to watch fireworks.

“The whole city was running. I got extremely frightened and ran away from the promenade,” she said. “It was chaos.”

The Washington Post and McClatchyDC reporter Matthew Schofield contributed to this report.

This story was originally published July 14, 2016 at 3:01 PM with the headline "After Nice attack, French officials warn that terror threats will stalk for 'a long time'."