Authorities say fentanyl and methamphetamine were found at a home where first responders became sick after answering a call about suspected overdoses in a rural New Mexico county. Three people who were found inside the house died. A fourth person who was in the house and one of the first responders who became sick were still being treated at a hospital Friday. A doctor who saw the first responders exhibiting symptoms — including vomiting and dizziness — said their symptoms most closely resembled fentanyl exposure. However, the investigation into how the exposure happened and what caused it was ongoing.

Investigators in New Mexico are trying to identify a mysterious substance that may have contributed to the deaths of three people. The exposure also led to more than a dozen first responders to be briefly quarantined. Authorities were called to a suspected drug overdose Wednesday. They found four people who were unresponsive inside a home in a rural town east of Albuquerque. Three of the people who were in the home died. First responders were evaluated after some began coughing, vomiting and experiencing dizziness. Medical workers checked nearly two dozen people, mostly first responders. Hospital officials said most experienced no symptoms and were discharged. Three were being monitored.