A rider feared helium would beryllium "hacked to decease underground" during an onslaught connected a London Tube bid which near a antheral successful hospital.
The witnesser said helium was travelling connected a Jubilee Line bid connected Friday erstwhile determination was "a immense commotion" and helium saw a antheral holding "a foot-long achromatic machete".
He said the unfortunate had suffered "a heavy gash" to his caput during the attack.
Police said 1 antheral was arrested portion different antheral had been taken to infirmary successful a unchangeable condition.
British Transport Police (BTP) were called to Green Park underground presumption connected the borderline of Mayfair successful cardinal London astatine 18:45 BST implicit reports of a stabbing.
The witness, who asked not to beryllium named, said radical connected the bid had "started screaming" and "there was a stampede to the beforehand carriage" erstwhile the onslaught began.
He said the intercom successful the carriage was not moving truthful the operator could not beryllium alerted and passengers were near defenceless arsenic the attacker "taunted" them.
"The attacker went backmost down the train. We heard screaming but we don't cognize what happened.
"He past came backmost and stood astatine the other extremity of the carriage taunting america and making retired helium was going to interruption down the doorway of the carriage," helium said.
The witnesser said the Tube bid yet stopped and equipped constabulary arrested the attacker, who did not defy them.
He added that it had been "completely and utterly terrifying" and "for astir 10 minutes I genuinely thought I would beryllium hacked to decease underground".
BTP said 1 antheral had been arrested connected suspicion of inflicting grievous bodily harm.
Green Park presumption was closed pursuing the onslaught but has since reopened.
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