NASHUA, NH. (WGGB/WSHM) -- We continue to follow developing news out of Nashua, New Hampshire from Monday afternoon. Three firefighters were injured during a gas explosion while responding to a fire at the Greater Nashua Mental Health Center.

According to our affiliates in New Hampshire and Boston, one of the firefighters has been discharged from the hospital. However, the other two are staying in the hospital overnight with non-life-threatening injuries.

The explosion sparked a four-alarm fire. Nashua Fire Rescue Chief Steve Buxton says, “We got it under control as fast as we could.”

Fire officials say they were originally called to check out a reported gas leak. They were about to enter the building when the explosion happened just moments later.

Some were briefly trapped but were able to make it out before flames spread, and the building collapsed. “Responding for a gas leak, arrived on scene, called for more resources, explosion took place, three firefighters injured,” he continues.

Around 40 people inside the facility were able to escape before the explosion. As the building became structurally compromised, all firefighters were ordered to evacuate and had to battle flames from outside.

Buxton goes on to explain, “We encountered water supply issues and damage to the building. We weren’t able to get far inside before it started to collapse.”

Officials say the fire and gas leak were contained to the facility and posed no threat to surrounding buildings. However, an emergency alert was issued to nearby neighbors, warning them to extinguish any open flames and be prepared to evacuate.

The fire marshal says the incident serves as a good reminder to call 911 and leave the area if you happen to smell gas.

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