Nearly one year into the District’s use of a private ambulance service to improve 911 response times and the fire chief is acknowledging the department is "struggling" with the availability of advance life support medic units. Those are the ambulances staffed by paramedics who are supposed to respond to the most critical emergency calls like cardiac arrest. In a message sent to fire fighters and obtained by News 4’s Mark Segraves, Chief Gregory Dean said response times for the advance life support units have not improved despite the addition of the private ambulance service.