UK train stabbing: Witnesses recall stabbing victims fleeing through carriages in terror on train bound for London

Witnesses say victims of a mass stabbing on board a train bound for London were forced to flee their alleged attacker through the carriages.

Nine people have been left with life-threatening injuries and a tenth sustained a non-life threatening wound after the stabbing on a train near Cambridge in the United Kingdom at 7.42pm (6.42am AEDT).

Two people have been arrested in connection with the incident, police said.

A witness to the stabbing told the BBC he saw a man raise the alarm to fellow passengers as he bolted through the carriage with a bloodied arm.

The man recalled hearing him say "they've got a knife, run".

He also said another passenger was seen collapsed on the floor of the train.

Another witness, who was on the platform at Huntingdon when the train approache