LONDON — For the first time, London’s Metropolitan Police activated their “run, hide and tell” warning on Saturday night as terror struck the heart of the city.

As a van veered off the road and barrelled into pedestrians on the busy London Bridge and three men fled the vehicle and attacked people, the police issued an alert through social media.

The alert, to be used in the event of a weapons and firearms attack, warned people in the area to run away from any threat, rather than surrender or attempt to negotiate. The authorities asked Londoners to “remain calm, but be alert and vigilant”.

The alert read: “Run — to a place of safety. This is a better option than to surrender or negotiate. If there’s nowhere to go, then ... Hide — Turn your phone to silent and turn off vibrate. Barricade yourself in if you can.

“Tell — the police by calling 999 when it is safe to do so.”

Several people said they were ordered by the police to stay inside pubs and restaurants as the carnage raged outside. Mr Alex Shellum at the Mudlark pub said a woman had come into the bar “bleeding heavily from the neck”, telling the BBC: “It appeared that her throat had been cut.”

In an information video about the advisory, Metropolitan Police’s Assistant Commissioner Mark Rowley said the instructions were based on proven advice.

“Everyone’s aware of the terrorism challenges across the world,” he said. “It can never cater for every possible eventuality and, if someone acts on instinct and perhaps decides to fight because they have no choice, we would never criticise them for that.”

Contrary to the alert, some people met the attackers head-on in an attempt to rescue victims, fighting back with chairs and pint glasses.

Mr Gerard Vowls, 47, said he saw a woman being repeatedly stabbed, and threw chairs, glasses and bottles at the attackers in a bid to stop them.

“They kept coming to try to stab me ... they were stabbing everyone. Evil, evil people,” he told The Guardian newspaper.

Reactions to the warning were mixed, with some seeing it as a show of weakness rather than practical advice.

Mr James Brown posted on Facebook: “We shouldn’t have to run and hide ... It’s only gonna get worse! The government needs to wake the f*** up!!!”

“How great this country now is, we have gone from fighting our enemies, to now run, hide, tell. Unbelievable!!!!,” added Ms Lydia Butler on Facebook.

In Singapore, the Ministry of Home Affairs has created a similar “Run, Hide, Tell” advisory regarding what to do in the event of a firearms or weapons attack.

The advisory has been tested in mock scenarios. AGENCIES