Police said two people had been arrested in connection with the attack on Saturday night.

Local authorities have not commented on the identities of those injured or arrested or the possible motive for the attack.

British Transport Police said it was investigating a "major incident" and was working with counter-terrorism officers.

Police initially treated the mass shooting as a "terrorist attack" when they received the emergency call, but later withdrew that statement.

Local police chief Chris Casey called the shooting a "shocking incident" and said he could not provide any further details.

Witnesses on the train said the attack lasted 10 to 15 minutes, but described it as "a lifetime."

Other passengers on the train said they saw wounded people running from a man wielding a knife.