The horrific Paris attacks that unfolded on Friday the 13th were celebrated by Isis-affiliated Twitter accounts, as the Islamic State claimed responsibility for what is the worst attack in France since World War II. 

Over 120 people have been killed while more than 200 were injured after eight terrorists launched coordinated attacks at a concert hall, restaurants and cafes, and near the Stade de France stadium in Paris. 

Before the Islamic State claimed responsibility through an official statement, Isis tweeps were seen 'celebrating' the deadly attacks on Twitter. 

"While no group has yet claimed the attack, the well-coordinated and well-disseminated campaign by IS fighters and pro-media might be an indication to a role by Isis," Rita Katz, Director of SITE Intelligence Group, said in a post on the website

"The way Isis supporters have embraced this attack appears much more coordinated at a much earlier stage than massive reactions to past attacks. In these past cases, Isis supporters speculated and hoped that Isis was behind those atrocities, but did not actually assert that the group was behind those respective attacks with such unanimous confidence as seen today," she said. 

Some jihadists also took to Twitter to point out how the nature of the Paris attacks hinted at an Isis role instead of an Al Qaeda attack. 

A jihadist with Al Qaeda affiliate Al Nusra Front said: "Al Qaeda focuses mostly on political and military targets instead of civilians. That's why this could be an Isis attack." 

Isis had threatened to attack Paris in several menacing videos released by the group, and Isis-affiliated Twitter accounts claimed the attacks were in response to French airstrikes in Iraq and Syria. 

French President Francois Hollande called the Paris attacks 'unprecdented' and declared a national emergency. He also ordered for the closure of France's border to ensure terrorists behind the attack do not escape.