Normal people would think 1 (if any) with a hand extinguisher might actually suffice,
Some types of portable fire extinguisher produce lethal gas when applied to burning metals as well as producing corrosive residue and an exothermic reaction.
"Flame retardant treatments such as brominated ploymers release dioxins and dibenzofurans and chlorinated polymers produce hydrogen chloride dioxin volotile compounds that are hazardous".
Fire Properties of Polymer Composite Materials By Adrian P. Mouritz, Arthur Geoff Gibson
The crap left after the fire, given it is in a confined space is itself a hazard, it is no surprise that emergency crews should hang around to secure the scene and have breathing apparatus to hand to effect further response or rescue.
Numerous fire crews and accident investigators responding to military jet crashes have been hospitalised even though they were wearing PPE.
20% to 40% of impact survivable fatalities are caused not by flame but toxic gasses.
The first gulp of carbon monoxide disorientates the second gas incapacitates and prevents your escape.
So think about that before you run into a smokey airframe.