London's Air Ambulance hopes to save even more lives as they become the first in the UK to carry blood on board its aircraft and cars.
They hope the blood will help medics save more lives at the scene of an accident before a patient is transferred to hospital.
Its helicopter and rapid response cars will carry a box with four emergency units of O negative blood which can be given to people from any blood group.
Around 160 people in the capital die at the scene of an accident each year, with a proportion of these dying from major blood loss.
These accidents are most often road crashes but also include people falling from heights, railway injuries and industrial incidents.
Every year staff from London Air Ambulance process around 100 "code reds" which involve alerting a hospital that it needs to have blood ready for a patient suffering severe blood loss.Being able to administer blood at the scene could save some of these lives.