Was a 3-alarm response. Town of Groton (which the separate city is within) has a lot of departments. Here is what departments I can remember that responded.
From within Groton;
City of Groton
Poquonock Bridge FD
Sub Base FD
Electric Boat Fire
Noank Fire
Old Mystic Fire
Mystic Fire
Groton Ambulance
Mystic River Ambulance
Unsure if Center Groton and Groton Long Point FDs responded.
Other Towns / Departments outside of Groton
New London Fire (RIT / Fast initially)
Ledyard Fire (Engine)
Gales Ferry Fire (Ladder)
Mohegan Tribal Fire (RIT / Fast)
Waterford FD (station coverage with at least 2 Engines)
Other ambulances including New London and Montville (unsure)