More sonic meteors?
Interesting set of inputs on the
Spokane-News facebook page, which is the ONLY source of actual local news.
Several people report hearing gunshots or fireworks at the same time. If they were in the same neighborhood, you could assume it was gunshots or fireworks. Or a repeatedly backfiring car, which can be much louder than gunshots. But they're all over town, and each of them says the sound was close by.
A couple years ago there was a similar set of "close everywhere" booms. Those were definitely traced to a large meteorite that passed over Spokane and fell somewhere in Montana.