Abstract: A system for extinguishing fires is provided which is compliant with ANSI/UL 1254 1999. The system comprises a fire extinguishant liquified gas which is EPA compliant, an ammonium fire extinguishing material, a polymeric gelling agent that interacts with fire extinguishing substances (a) and (b) to promote the formation of a stable, gel-like suspension there between, and a viscosity reducing agent which facilitates the flow of the mixed phase agent from the extinguisher so that a sufficient amount of the fire extinguishing substances (a) and (b) is discharged from the system in response to heat generated by a fire in an area proximate to said fire extinguisher system to extinguish the fire in a manner compliant with ANSI/UL 1254 1999.