People need to learn lifesaving skills in case they are caught up in a terror attack in the UK, a team of senior military and civilian medics has said.
They say people need to know how to help each other because it could take some time before it is deemed safe for paramedics to arrive on the scene.
Their app, called CitizenAID, offers step-by-step advice.
The idea is supported by counter-terrorism police. Security services say a UK terror attack is highly likely.