The 3 things you MUST do if you're caught in an attack like the Huntingdon train stabbings

It's the stuff of nightmares. To be trapped on a train, terrorised by men of violence armed with knives. Mercifully, such events are incredibly rare in this country, but the horrifying scenes from Saturday night remind us we must never take our safety for granted. So what should you do if you were caught up in a marauding knife attack? The advice is simple: Run. Hide. Tell.

(1) Run: Your first act must be to run - and to insist that others do the same. Running is an act of wisdom, not cowardice. The worst possible thing would be to become another casualty or hostage - not least because that would make the task of the responding emergency services harder than it already is.

Of course, running is easier said than done within the closed confines of a train, but the principle remains the same. Leave your personal belongings behind, and put as much distance between you and any attacker(s) as possible. And do not put yourself or others in danger by attempting to film what is happening.

(2) Hide: If you can't run, you need to hide. Once again, difficult to do on a train, but try to secure yourself and others in a locking toilet. Use luggage as barricades and to slow the progress of attackers. As a last resort, use hard-shelled suitcases as a form of defence.

Keep still, turn your phone to silent, and remain as quiet as possible.

(3) Tell: Once it's safe to do so, dial 999. Keep the details as accurate and succinct as possible: where you are; what's happening; details of the suspect(s). Answer any questions from the operator as swiftly and simply as you can. Once that is done, you need to follow the example of Fred Rodgers, the American TV presenter whose mother famously advised: "Look for the helpers". This is what the police are trained for.

This is what they are equipped for. And they are the ones who, time-and-again, will put themselves in harm's way to protect you and those you love.

• John Sutherland is a retired former chief superintendent and senior hostage negotiator