Many couldn't bear sitting through a video of the 2016 Nice massacre at the Paris trial
Many couldn't bear sitting through a video of the 2016 Nice massacre at the Paris trial AFP

A video showing how an Islamist extremist ploughed his truck into a crowd in Nice killing 86 people while France was celebrating its national day sparked anguish and horror at the attack trial on Thursday.

Tunisian Mohamed Lahouaiej-Bouhlel, 31, was killed by police after a four-minute rampage down the seaside embankment of the Promenade des Anglais, where thousands of locals and tourists were celebrating July 14 or Bastille Day in 2016.

The footage, never shown in public, was presented as evidence at the trial of eight people suspected of helping Lahouaiej-Bouhlel or knowing of his intentions.

Witnesses and survivors gasped in horror as the screen filled with people mowed down by the criss-crossing vehicle, their bodies broken and squashed under its wheels.

Presiding judge Laurent Raviot had warned the courtroom that the images, filmed by a bystander, were "terrifying".

When the lights were dimmed for the screening, a sharp intake of breath went through the courtroom, followed quickly by several cries of anguish.

Veronique Marchand, a 79-year old woman whose husband died in the attack, screamed and left the room. Her cries continued to be heard from the corridor through the closed doors.

Another woman, among the plaintiffs, also left the room after bursting out in tears, just as the footage showed the killer swerving his truck from side to side to mow down as many people as possible.

Another scene shows a jazz band finishing their performance, and then the truck ploughing from behind into the applauding audience which was completely unaware of the mortal danger until it was too late.

"I now think that I shouldn't have watched this," said Jean-Claude Hubler, president of the "Life for Nice" survivors' association, after the lights went up, revealing tearful faces in shock and sadness.

"It's hard to watch but this is what happened," another man said.

The judge ordered all smartphones and laptop computers shut down during the viewing, including those of reporters.

Seven psychologists were present to assist anyone under duress, as well as firemen and police.

Some of the accused watched the footage of the massacre, others looked down.

The video was resealed as evidence immediately after the screening, and is not to be shown again.

The seven men and one woman standing trial in Paris are accused of crimes ranging from being aware of the killer's intentions to providing logistical support and supplying weapons.

Only one suspect, Ramzi Kevin Arefa, faces the maximum penalty of life imprisonment if convicted as a repeat offender. The others risk between five and 20 years in prison.

The trial, which is set to last until December 16, is the latest legal process over the wave of Islamist attacks that have struck France since 2015.