New Mexico authorities said three people are dead and more than a dozen first responders are being treated for exposure to an unidentified substance after being called to a home for a suspected drug overdose. New Mexico State Police say three of the four people who were found unresponsive inside the home east of Albuquerque have died and the other is being treated at a hospital. During the response, authorities said, 18 first responders were exposed to the substance and began experiencing symptoms that included nausea and dizziness. All of the first responders were transported to the University of New Mexico Hospital, where they are being monitored.