Since the three day terror attack that started in France on January 7 with the attack on satirical newspaper Charlie Hebdo, 19,000 websites of French-based companies have been targeted by cyber attackers, AP reports.

According to Admiral Arnaud Coustilliere, the French military’s head of cyberdefense, most of these attacks were carried out by three Islamic hacker groups: Middle East Cyber Army, Fallaga team and Cyber Caliphate.

This unprecedented avalanche of cyber attacks targeted both government sites and that of big and small businesses. Most were low-level DDoS attacks, and some were web defacements.

In a report published on Wednesday, Radware researchers noted that Islamic hacker group AnonGhost has also launched a “digital jihad” against France.

“Over the last few days, AnonGhost has brought down a number of French websites, replacing the pages with a manifesto and a series of disturbing images,” they shared.

“Several websites in a number of towns in the outskirts of Paris have been hacked and covered with an image of an ISIS flag. The front pages of the official municipality websites have been covered with the Jihadist militant group’s black flag, play Arabic-language music and feature the message: ‘The Islamic State Stay Inchallah, Free Palestine, Death to France, Death to Charlie.’ Some of the sites that have been taken over include those of the towns of Jouy-le-Moutier, Piscop, Goussainville, Val D’Oise and Ezanville. All of them are situated around the French capital.”

Other targets included the websites of a bank, a telecom, and a media firm.

Cyber activist group Anonymous on Thursday launched an operation dubbed #OpCharlieHebdo, whose aim is to target and takedown jihadists websites and social network accounts belonging to terrorists. They have the public to participate by reporting Twitter accounts of suspected terrorists.

“The hackers associated with the international network took responsibility for bringing down Ansar-Alhaqq.net, a religious website in French and Arabic that waves an Islamic flag, with a distributed denial of-service (DDoS) attack,” Radware reports.