A system and method for acoustically detecting the firing of gunshots indoors employs multiple microphones (15, 20) which are utilized individually and in combination to detect sounds inside a building or other structure and, upon sensing a loud impulsive sound which is indicative of a gunshot, processing signals from both microphones (15, 20) to determine if the sound is that of a gunshot. The system and method relies on the acoustic signature of the noise as collected, with the acoustic signature being analyzed to arrive at values which are then compared to adjustable levels that signify a gunshot.