When a person's heart stops or a person is choking, treatment should be started before calling for help. In the United States, emergency medical care can be accessed by calling 911. The caller should give the dispatcher a full description of the person's condition and how the injury or illness developed. The caller should not hang up until told to do so. If several people are present, one should call for help while another begins assessment and first aid.
Assessment should take less than 1 minute per injured person. In each case, the rescuer should consider whether the situation is life threatening, urgent but not life threatening, or not urgent. Difficulty breathing and massive bleeding are life threatening, but a broken hand or foot can almost always wait for treatment, no matter how painful. When there are many people with serious injuries and resources are limited, rescuers may need to provide treatment only to those people who rescuers believe have a chance of surviving.