1522 hours. The Commack Fire Department was dispatched along with Commack Volunteer Ambulance Corps to 37-39 Vanderbilt Motor Parkway in regards to a carbon monoxide detector activation with subjects feeling ill. FD and EMS units arrived to find 20 people reporting carbon monoxide exposure like symptoms. Fire Department personnel evacuated a number of stores and crews entered the building to locate the source of the problem. Commack Ambulance began patient assessment, calling for ambulances from Deer Park, Dix Hills, North Babylon, East Brentwood Greenlawn, Kings Park and  Smithtown. A Field Physician was called in to evaluate all of the patients. The doctor determined that 9 victims should be transported and the other 11 could be treated and released from the scene. The source of the carbon monoxide was found to be a defective water heating unit in a hair salon. The Smithtown Fire Marshals Office was called in and is handling the investigation.