London's Metropolitan Police department has released a video advising people how best to protect themselves from an armed attack.

The video's top tip: run if you hear gunshots, unless that puts you in greater danger.

Otherwise hide, ideally behind a physical barrier.

The advice came in a four-minute film released Friday.

British security services are on heightened alert because of the recent attacks in Paris, and the government has set the official threat level as "severe" indicating an attack is highly likely.