ISIS tweeted about bomb blast before only

May 23: Global terrorist organization ISIS (Islamic State of Iraq and Syria) has claimed responsibility for the gruesome blast which killed 20 people and fatally injured over 50 in Manchester, England, the deadliest attack in Britain in a decade.

ISIS said that this blast was just the beginning and that more brutal terror attacks will follow. Meanwhile, ISIS supporters and sympathizers across some parts of the world have celebrated this terror attack, claiming it to be a massive victory.

Hours before the suicide bombing, the Twitter account of a possible ISIS sympathizer tweeted about the planned terror attack at Manchester Arena in England. The Twitter account seemed to be suspended immediately following the bombing.

"Tomorrow night, I will go to the Manchester Arena Grande concert and throw my handmade grenade in there," the person wrote on another forum.

The concerned authorities have launched an investigation to find the source and authenticity of the posts. Meanwhile, an unverified video has appeared on social media claiming ISIS was behind the attack in England.

On the other hand, all the European countries have become alert after the attack in England. Security has been tightened in major cities and intense investigations are being carried out in populous places. The US has also alerted its intelligence agencies and police force to be alert fearing that it could be the next target.

British Prime Minister Theresa May condemned the attack and expressed solidarity with those who were bereaved.