Nashua firefighters responded to a gas leak at 440 Amherst St in the afternoon on 2/2/26. Engine 5 and Ladder 1 arrived on scene and shortly after arrival, the gas main/building exploded injuring 3 firefighters. A 2nd alarm was immediately struck followed by the 3rd and 4th alarms. Companies had long supply line lays down Amherst Street due to multiple dead hydrants in the area. Companies remained defensive using multiple master streams and big handlines to knock down the fire. Fire companies remained on scene through the night hitting hot spots. The fire remains under investigation.