- Video report by ITV News Correspondent Richard Pallot
Teenagers and children are being targeted in a new anti-terror awareness video - featuring a number of high-profile figures.
The drive attempts to teach youngsters the key safety steps to follow in the event of a terrorist attack.
It comes as police expressed concern witnesses are willing to take photographs or record video during or directly after incidents.
Officers highlighted the recent attack on an underground train at Parsons Green station, where images of a partially exploded bomb appeared online within minutes.
Survivalist Bear Grylls, sports stars Jamie Vardy, James Haskell and Jade Jones all feature in the video, part of the "See It Say It Sorted" campaign.
The UK terror threat level remains at severe after five attacks rocked the country over the past year.
Met Police Deputy Assistant Commissioner Lucy D'Orsi said: "We appreciate that talking to young people about terrorism can be scary, for parents and children alike.
"But the atrocities in London and Manchester have sadly resulted in some of the youngest victims of terror this country has ever seen, and if we are able to teach children to act in a way which could potentially save their lives then it is our responsibility to do so.
"We are particularly concerned when we see people - young and old - using their mobiles to film scenes when they should be moving away from the danger. The recent incident in Parsons Green is a good example of this.
"Our research showed that many young people think filming would be a good thing to provide evidence for police. We must get them to understand that the priority must be their safety."
Police have run a number of public information campaigns highlighting the main advice to follow if an attack happens.
It states that people should run if they can, or if not hide, and then alert authorities only when it is safe to do so.
As part of the drive police want to see the message taught in schools and colleges to 11 to 16-year-olds as part of the citizenship strand of the national curriculum.
Security minister Ben Wallace also backed the campaign.
"This should not stop young people from going out and enjoying the best years of their lives but being alert, not alarmed and knowing the run, hide, tell advice could well be life-saving," he said.
"Today, I am encouraging parents to discuss this important advice with their children so that they know how to act should the worst happen."
The NSPCC said it has received 300 contacts from young people anxious about terrorism since April.
John Cameron, head of helplines at the charity, said: "Adults can help a child by listening to their worries, reassuring them these events are rare, and teaching them to run, hide, and tell."