LONDON - A knifeman slashed a man's throat at a busy London tube station shouting "this is for Syria" before being Tasered by the police, according to reports.
The suspect attacked the man at Leytonstone underground station shortly after 7pm (3am on Sunday Singapore time). Another three people are thought to have been injured.
Eyewitnesses claimed the man shouted "this is for Syria" and "all of your blood will be spilled" during the terrifying attack, Britain's Daily Mail said.
The Metropolitan police Tasered the suspect and arrested him, the Mail said.
One witness said the victim was an "elderly" man with a younger female family member, while another said the attacker had a long knife, which looked like a machete, according to Britain's Daily Express.
A video taken by another witness shows a big pool of blood just outside the ticket barrier as police confront the attacker, then taser him before putting handcuffs on him and arresting him.
A Scotland Yard spokesman said: "Police were called at 19.06 hours on Saturday, 5 December, to reports of a stabbing at Leytonstone underground station. The male suspect was reportedly threatening other people with a knife.
"Met officers attended the scene. A man was arrested at 19.14 hours and taken to an east London police station where he remains in custody. A Taser was discharged by one of the Met officers.
"Officers from British Transport Police are now dealing with the incident at the scene. We are aware of one man having sustained serious stab injuries. We await details of any other injuries."
One person, who claims to have witnessed the attack, took to Twitter to reveal details of the horror.
Laurynas Godvisa said: "So as I was going to Leytonstone station was dressed to go to Christmas dinner with people from work.
"As I walked down I just saw a lot of people running but I ignored it and kept walking to get my train, but suddenly what I saw I couldn't believe my eyes and what I saw was one guy with a knife and a dead guy on the floor.
"I was so scared I ran for my life. After good 10-15 police came and got the guy and arrested him.
"And as he was coming out this is what he said "This is what happens when you f*** with mother Syria all of your blood will be spilled"."
People who had just got off the Tube ran back onto the train in a bid to escape the attacker, said the Express.
A spokeswoman from London Ambulance Service said: "We were called at 7.09pm to reports of an assault at Leytonstone underground station.
"We sent a number of resources to the including our joint response unit, an incident response officer, an ambulance crew and London's Air Ambulance to the scene.
"We treated a man for stab wounds.
"He was taken as a priority to hospital escorted by the doctor from London's Air Ambulance. "