Mass. Gen. Laws ch. 111C, § 25

When a class I, II or V ambulance transports a patient receiving care at the paramedic level of advanced life support the ambulance shall be staffed in accordance with regulations promulgated by the department, with a minimum of 2 emergency medical technicians, only 1 of whom shall be certified at the EMT–Paramedic level; provided, however, that the service staffing a class I, II or V ambulance may staff the ambulance with more than 1 emergency medical technician certified at the EMT–Paramedic level.