What's the safest way (for residents and first responders) to store ammunition at home?

For those of us that own guns and store ammo, what's the safest way to store it so that if there's ever a fire, the ammo won't pose a risk to anyone in the home or to any firefighters that may enter to fight the fire or clear the home? Of course a homeowner should warn first responders about the presence of guns and ammo, but is that enough?

It's typical to use a gun safe or locking gun cabinet (these are legally required for gun owners with children in the home anyway). Are those sufficient to ensure the safety of firefighters that may enter during a fire? If not, what's the right way to store the ammo?

Thanks!