A man stabbed three people at an east London Tube station, and authorities say they are investigating the attack as a terrorist incident.
The assailant, believed to be 29, was subdued with a stun gun and arrested Saturday night, London's Metropolitan Police said.
One man, 56, suffered serious injuries, but they're not considered life-threatening, police said.
Two others had minor injuries in the attack.
Police are looking into reports that the suspect yelled, "This is for Syria," during the attack, said Chioma Dijeh, a spokeswoman for the Metropolitan Police.
"We are treating this as a terrorist incident," said Cmdr. Richard Walton, head of the Metropolitan Police Counter Terrorism Command.
"I would urge 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."
