Emergency medical services (EMS), also known as ambulance services or paramedic services, are agencies that deal with medical emergencies, mostly by sending ambulances or other vehicles to help people who are severely ill or injured. Their job is to treat these people at the incident and to take them to a hospital if needed. There are several types types of staffing. Most Ambulances and other medical vehicles have personnel who provide Advanced levels of Emergency Medical Care. This is called Advanced Life Support (ALS). Sometimes it is called Advanced Cardiac Life Support (ACLS). Some ambulances or other medical vehicles also have staff with more basic training,and they are known as Emergency Medical Technicians (EMTs). They provide Basic levels of Emergency Medical Care. This is called Basic Life Support (BLS). Sometimes there are both on Ambulances. Doctors sometimes assist with care.