Get everyone outside and call 911. This is an emergency! Advise the dispatcher whether or not you, or anyone else in the building is exhibiting signs of carbon monoxide poisoning (headache, lightheadedness, nausea, fatigue). This will help the dispatcher send the proper units to your location. If no one is exhibiting symptoms, the Fire Department will respond non-emergent, to check carbon monoxide levels. If symptoms are being exhibited by one or more people, you can expect the Fire Department and EMS to be sent to your location "Priority One" (lights and sirens) to begin helping those who have been affected.