Unknown substance sickens first responders in Mountainair, New Mexico

An unknown substance inside a rural Mountainair home left three people dead, sent more than a dozen first responders to hospitals, and forced officials to answer the hardest question in a hazmat event: how to protect the public when the hazard is still unidentified. New Mexico State Police said the incident unfolded Wednesday, May 20, 2026, in Mountainair, a small community east of Albuquerque, after crews were called to a suspected drug overdose.

State police said four people were found unresponsive inside the home. Three died, and the fourth was taken to a hospital in Albuquerque. During the response, first responders were exposed to the substance and began reporting nausea, dizziness, coughing, vomiting and headaches, turning what began as a medical call into a wider emergency involving firefighters, EMTs and hazmat crews.

University of New Mexico Hospital said 23 patients exposed to the unknown substance were assessed and decontaminated after being transported there. Most of those patients were first responders who had no symptoms and were later discharged. Three symptomatic patients remained under monitoring Wednesday evening, and two first responders were listed in serious condition. Mountainair EMS Chief Josh Lewis, who was the first to enter the residence, was hospitalized overnight for observation.

Mountainair Mayor Peter Nieto said public works crews determined the illnesses were not tied to carbon monoxide or natural gas exposure. He said the exact cause remained unknown, but early indications were pointing toward narcotics as a possible factor. Investigators said they did not believe the substance was airborne and instead thought the exposure may have happened through contact. Albuquerque Fire Rescue hazmat teams assisted at the scene as officials worked to keep the incident contained and reassure residents that there was no broader threat to the public.

Mountainair volunteer firefighter Antonette Alguire said she helped give CPR outside the home and watched EMTs and firefighters begin to get sick at the heliport, a sign of how fast the scene escalated. Reports also said some of the deceased were found after they failed to show up for work, adding a painful local dimension to a death investigation now tied to an unknown material, a sickened response force and a community still waiting for answers.