They can be members of the public, who have received training in life-saving interventions such as defibrillation, off duty paramedics, nurses or medical doctors, or indeed professionals from a non-medical discipline who may be nearby or attending emergencies, such as firefighters.
[1] Community first responders are there to provide assistance to those with a medical emergency, and most importantly to start and maintain the chain of survival in cardiac arrest patients until a fully equipped ambulance arrives.
The schemes have since expanded to more populous areas, where the benefit of early intervention can still prove life-saving, and the volume of people available to ambulance control assists them with meeting response time targets such as ORCON.
[3][4] A UK review found that first responders were more likely to attend the scene of an incident before an ambulance in rural areas, for neurological conditions including stroke, and for heart and breathing problems.
Types of call which responders may not be asked to attend (or be stood down if already en route) include drugs related problems, domestic violence and abusive patients as well as dangerous scenes such as traffic collisions or building sites.
In most schemes, they are expected to drive under normal road traffic laws, and are not permitted to claim exemptions or use blue lights and sirens (as a matter of policy, rather than legal restriction).