British Prime Minister David Cameron says there are strong indications that an attack in London could be a "terrorist incident."
Speaking at a press conference in Paris, Cameron said the attack was "absolutely sickening" and announced he was cutting short his trip to return to London.
British police on May 22 said they shot and wounded two suspected attackers after a man was killed outside a military training facility in southeast London.
Media reports said the victim was thought to be a British soldier.
Police said the suspected attackers were believed to have been carrying weapons.
Eyewitnesses said the victim was hacked to death with machete-like knives.
In footage broadcast on ITV, the alleged attacker says, "We swear by almighty Allah we will never stop fighting you."
Based on reporting by AP, BBC, and dpa