A blood supply shortage in the US has reached a “crisis” level, according to the American Red Cross, which says it is the second time in its 150-year history that levels have been this low.

Factors including wildfires and extreme heat have combined to create the current situation, Dr Courtney Lawrence, who works with the American Red Cross, told the BBC.

Supply levels dropped by a quarter just last month. The crisis has struck during summer, when the amount of blood needed by hospitals typically increases.

That is because of an increased number of car accidents and more people spending time outdoors, resulting in more injuries that require blood transfusions, Lawrence said.