Gas Explosion Destroys Nashua Mental Health Clinic, Injures Three Firefighters

On a gray Monday afternoon in Nashua, New Hampshire, the smell of gas began drifting through the halls of a busy mental health clinic just as appointments were getting underway.

Firefighters arrived at Greater Nashua Mental Health’s Amherst Street building a few minutes after a 2:15 p.m. 911 call on Feb. 2, officials said. They reported smelling gas and hearing a hissing sound, the telltale sign of a ruptured line. As they started moving people out, the building exploded.

The blast rattled homes and businesses along the commercial strip about 45 miles north of Boston, triggered a four-alarm fire and partially collapsed the structure. Three firefighters were injured. Roughly 60 staff members and patients who had been inside escaped without harm.

The one-story clinic at 440 Amherst St. was later declared a total loss.

“We had an unfortunate situation where three of our firefighters were injured,” Nashua Fire Chief Steve Buxton told reporters. “But all of the civilians were able to safely evacuate with no injuries and no deaths.”

Citywide alert, shaken neighbors

The explosion prompted a citywide emergency alert to cellphones warning residents of a natural gas leak and instructing them to extinguish open flames, avoid using ignition sources and be ready to evacuate certain areas if necessary. For many in Nashua, the sudden alert, shaking buildings and column of smoke evoked memories of the deadly gas explosions that struck Massachusetts’ Merrimack Valley in 2018.

“I thought a tree had fallen on the house,” said nearby resident Jesci Larochelle, who described her home shaking from the force of the blast. “I started looking for damage and then the alert went off on my phone.”

At a nail salon not far from the clinic, business owner Leanna Wong said the explosion blew open her door.

“It shook, and my door opened,” she said. “I’m just worried. My God.”

Investigation focuses on gas service line

As of Thursday, state and local investigators had not pinpointed the exact cause of the blast. New Hampshire State Fire Marshal Sean Toomey said his office is focusing on the natural gas service line that fed the building and on equipment where the line entered the structure.

“We know there was a 911 call for a smell of gas,” Toomey said. “We’re going to speak with everyone to see where it was strongest and work back from there.”

One working theory investigators are exploring is whether ice falling from the roof or an adjacent structure struck and damaged the exterior gas line or meter assembly. The region had been in a prolonged cold spell with snow and ice accumulation—conditions that can add weight to roofs and create heavy ice sheets near building edges.

Officials stressed that the falling-ice scenario remains unconfirmed. Liberty Utilities, the gas provider for Nashua and much of southern New Hampshire, said crews responded to the scene and are assisting investigators. No regulatory findings or allegations of fault have been made public.

A critical-care hub lost

The timing and location of the explosion—at a community mental health center during business hours—have sharpened concerns about the resilience of critical-care facilities that rely on gas lines and aging infrastructure.

Greater Nashua Mental Health is one of the state’s designated community mental health centers, serving a 10-town region that includes Nashua and its surrounding communities. The nonprofit, founded more than a century ago, provides outpatient counseling, psychiatric care and case management for children, adults and older adults, along with substance use treatment and homeless outreach.

In 2024, the organization became New Hampshire’s first Certified Community Behavioral Health Clinic, a federal and state designation meant to expand 24/7 crisis services and better integrate mental health, substance use and primary care.

The Amherst Street building played a central role in that system. It housed Open Access walk-in hours for new clients, making it a low-barrier entry point to services. It also hosted specialized programs, including services for deaf and hard-of-hearing clients and several older-adult and substance use disorder teams.

In a public notice after the fire, Greater Nashua Mental Health said the 440 Amherst St. clinic would remain closed and described the building as destroyed. Clients with in-person appointments at that location were urged to call the organization during business hours to make alternate arrangements. Two other sites on Prospect and Pine streets in Nashua remain open.

Mental health advocates say even a short-term loss of capacity at a hub like Amherst Street can have ripple effects, especially for people with serious mental illness, substance use disorders or communication barriers who depend on familiar providers and routines.

Emergency response and injuries

Nashua’s emergency response has drawn attention in its own right. The city is the only municipality in New Hampshire with a full-time, standalone Office of Emergency Management. Director Emily Martuscello and her team coordinated efforts among fire and police departments, public works, school officials, nearby hospitals and the American Red Cross.

Authorities said all staff and patients who had been in the building were quickly accounted for. St. Joseph Hospital’s Amherst Street location canceled appointments to keep roads clear for emergency vehicles, and a nearby charter school sheltered students in place until dismissal routes could be adjusted.

Buxton said the four-alarm fire was “pretty significant for the city,” requiring essentially all of Nashua’s firefighting resources plus mutual aid. Cold temperatures and ice hampered the flow of water, he said, and the continuing gas leak fed the flames until utility crews could secure the line. The fire was brought under control by early evening.

Three firefighters were transported to an area hospital with injuries that officials initially described as non-life-threatening. Buxton later said one firefighter was released that night, while two others with more serious but still non-life-threatening injuries remained hospitalized overnight.

Gov. Kelly Ayotte, who took office last year, said she had been briefed on the incident and thanked the “heroic efforts” of first responders.

Broader questions about gas safety

The explosion follows a string of high-profile emergencies in and around Nashua—including major fires, a plane crash and a deadly shooting in the past year—according to local officials. It also comes weeks after a natural gas explosion at a nursing home in Bristol Township, Pennsylvania, killed three people and injured about 20. In that case, federal investigators said the blast occurred hours after a gas odor was reported and a utility worker identified a leak on a meter set valve.

In New England, many residents still vividly recall the 2018 disaster in the Merrimack Valley, where overpressurized gas lines operated by Columbia Gas of Massachusetts sparked dozens of fires in Lawrence, Andover and North Andover. An 18-year-old was killed, and hundreds of homes were damaged or destroyed. The company later pleaded guilty to federal charges and paid millions in fines and settlements.

Those incidents, along with the Nashua blast, have raised questions about how well gas infrastructure is monitored and protected, especially at facilities that serve vulnerable people such as hospitals, nursing homes and mental health centers.

New Hampshire’s Public Utilities Commission oversees pipeline safety and will likely review findings from the state fire marshal’s investigation. Potential areas of scrutiny include whether external gas lines and meters are adequately shielded from weather, falling ice and vehicle impacts, and whether inspection schedules or building codes for critical-care facilities need to be updated.

For now, Nashua officials are emphasizing what did not happen.

“If this had gone off before firefighters started getting people out, we could be looking at a much different outcome,” one city official said, speaking generally about the sequence of the evacuation and blast.

In the days after the fire, patients and staff returned to the charred site only in passing, driving past yellow tape and burned-out walls on their way to other offices or temporary appointments. For many, the destruction of the clinic is both a close call and a new source of uncertainty: a reminder that the systems they rely on—pipes under the street, buildings they enter every week, the services that keep them afloat—can be fragile.

Rebuilding the facility and restoring its full slate of services will likely take months or longer. Determining precisely why the gas line failed, and what must change to keep it from happening again, may take even longer.