On the other hand, private ambulance services have contracts with local government to provide medical services or emergency transportation. The level of medical care provided by these professional services varies by contract. In some cities, private ambulances are only under contract for transportation of patients. In other areas, private services are responsible for providing emergency medical care as well. Private ambulance services are also commonly used to provide standby for large events, when a police or fire services alone would not suffice in an emergency.