This came up after reading on TV Tropes that the third season (yes, that season) seems to include in the episode "Urban Jungle" the fact that in "10 Seconds After People" (the lowest amount of time ever seen on the show) the helicopters would crash and fall from the sky in New York, for example, a la Aftermath.
Aside from how bad it's the season, the inclusion of that detail brings back to me that idea of how humanity became extinct/disappeared. Considering that something similar happens in Aftermath, could the possible reason in LAF be a Rapture-type scenario?