A forensic is at work at the site of a ramming attack which took place on Tuesday at a road toll in Incarville in the Eure region of northern France on Tuesday. AFP

The van was transporting prisoner Mohamed Amra to Évreux jail after a court hearing in Rouen when it was ambushed.

Justice Minister Eric Dupond-Moretti said he would join a crisis unit to address the emergency.

"All means are being used to find these criminals. On my instructions, several hundred police officers and gendarmes were mobilised,” Interior Minister Gerald Darmanin posted on X.

"This morning’s attack, which cost the lives of prison administration agents, is a shock for all of us," French President Emmanuel Macron posted on X.

"The nation stands alongside the families, the injured and their colleagues.”

The attack prompted a significant law enforcement operation in the northwestern region of France as authorities worked to secure the area and apprehend the assailants. The assault took place late Tuesday morning on the A154 freeway, which has since been closed.

Amra was under high surveillance and had recently been sentenced for burglary. He was also under investigation for a kidnapping and homicide case in Marseille, according to public prosecutor Laure Beccuau.

French media reported that Amra was nicknamed "La Mouche” (The Fly).

Beccuau announced an investigation into the attack, now considered a case of organized crime and murder. "At this stage, we mourn the death of two penitentiary agents in this armed attack, and two are in critical condition,” Beccuau said in a statement.

The investigation will also address organized escape attempts, possession of military-grade weapons, and conspiracy to commit crime.

Associated Press