President Donald Trump and House Speaker Paul Ryan have condemned the attack in Manchester.
"Dozens of innocent people, beautiful young children, savagely murdered in this heinous attack upon humanity," said President Trump. "I repeat again that we must drive out the terrorists and the extremists from our midst."
Speaker Ryan also discussed the need to stand against radical Islam.
"To deliberately target innocent children is cowardice in its most heinous form," said Speaker Ryan. "So we should not be surprised that ISIS has claimed responsibility for this attack, but we will never bow or bend to radical Islamic terror.
British Prime Minister Theresa May has raised the country's terror threat level to critical.
