The four were arrested on Monday and one was already charged on Wednesday with participating in a terrorist plot, while the other three are now appearing before a judge to be charged, added the source who asked not to not be named.
They are believed to be aware of the attacker’s plot and to have instigated him to carry it out, the source said, confirming a report first published in the The Parisian Daily.
The attacker, named Zaheer Hassan Mahmoud, 25, was arrested after the attack on terrorism charges and remains in detention.
The news of the arrests comes two days after a Paris court convicted 13 accomplices of the jihadist gunmen who slaughtered staff in January 2015 at Charlie Hebdo, which had published cartoons of Prophet Muhammad (PSL).
To mark the start of this trial in early September, Charlie Hebdo had reprinted the sketches in a typically provocative style.
Three weeks later, the Pakistani injured two people outside the magazine’s former offices, hacking them with a cleaver.
On October 16, a young Chechen refugee beheaded Professor Samuel Paty who had shown some of the cartoons to his students.
And on October 29, three people were killed when a young Tunisian recently arrived in Europe embarked on a stabbing frenzy in a church in the Mediterranean city of Nice.
President Emmanuel Macron’s government has introduced legislation to tackle what it calls radical Islamist activity in France, a bill that has sparked anger in many Muslim countries.