New Mexico authorities say three people are dead and more than a dozen first responders were assessed for possible exposure to an unidentified substance after being called to a rural home for a suspected drug overdose. New Mexico State Police said four people were found unresponsive inside the Mountainair home east of Albuquerque. Three died and the fourth was being treated at a hospital. Officials at the University of New Mexico hospital say nearly two dozen patients were asessed and decontaminated after being exposed to the substance. Most of them were first responders who displayed no symptoms and later were discharged.