Police in London say that are treating a knife attack in the city's subway system as a "terrorist incident."
According to the Metropolitan Police's Counter Terrorism Command, the man, who is believed to be 29 years old, stabbed three people, one of them, a 56-year-old man, sustained serious injuries.
NPR's Peter Kenyon reports that witnesses said they heard the alleged attacker shout "This is for Syria," as he tried to stab people. Britain recently joined an international coalition bombing Islamic State targets in Syria.
In a statement, the police's counter terrorism chief Richard Walton urged the public to "remain calm, but alert and vigilant."
"The threat from terrorism remains at severe, which means that a terrorist attack is highly likely," said Walton.
A video posted online shows police apprehending the man. A bystander shouts: "You ain't no Muslim bruv."
As The Guardian reports, the phrase has been picked up on Twitter by users who "say it is the perfect riposte to attempts to spread violence and terror in London – disowning and sidelining the attacker."