Three people died and more than a dozen emergency officials were hospitalized after suspected exposure to an unknown substance at a home in a small town near Albuquerque on Wednesday, the New Mexico State Police said.

Officers from the state police and the Torrance County Sheriff’s Office responded to the home in Mountainair, N.M., for what was initially reported as a possible drug overdose. They found four unresponsive people inside at around 11 a.m., the state police said in a statement. Three of the four have died, authorities added.

Peter Nieto, the mayor of Mountainair, a small town around 40 miles southeast of Albuquerque, said on social media that two of the people were found dead at the scene and another died later.

While responding to the incident, 18 emergency officials were exposed to the substance and began experiencing symptoms including nausea and dizziness, the state police said. Those officials, and the fourth person found inside the home, were taken to the University of New Mexico Hospital for quarantine and monitoring, the state police said, adding that two officials are in serious condition.

The authorities said they were in the process of investigating and identifying substance caused the deaths inside the home and the symptoms among the responders.

The incident prompted a large response by emergency and law enforcement teams, including from the F.B.I.’s Albuquerque office. Albuquerque Fire Rescue said its hazmat teams helped collect samples, identify substances and carry out decontamination efforts.

The state police said investigators believed the substance may have been transmitted through contact and did not believe it was airborne. The authorities said there was no threat to the public.

The University of Mexico Hospital said later on Wednesday that it had assessed and decontaminated 23 patients. Most of them, who did not show symptoms, were discharged. Three people who were showing symptoms remained under monitoring, the hospital said, adding that they had experienced headaches, nausea and vomiting.