Unfortunately ambulances in Japan blare their sirens any time they are transporting a patient, and because they are free some people use them like taxis. So you may see an ambulance at 2AM driving down a residential street blaring their siren at full volume, going 5 mph while the medics call around to various hospitals to see who will take their patient with an upset stomach.
Once I passed a moving ambulance with the siren on...while slowly riding my bike down an otherwise empty road.
The result is that Japanese people seem to tune out the siren. If the driver isn't also on the loudspeaker telling them insistently to move aside, they assume it's not a "real" emergency.
That's what we learned in fire fighting training. Everything that doesn't get destroyed by the fire and smoke will get destroyed by the water you use to put the fire out. A house on fire is lost. You just save people and animals and then you do whatever you need to protect the neighbouring structures.
Bob should have used some of his Fuji 9, that fixes everything!