By what looks like an asteroid or cometary impact. And it caused worldwide cooling, the extinction of the megafauna and the disappearance of the Clovis civilization in North America. This is a really interesting article (and a scholarly paper linked to in the piece). The entire world was changed with one cosmic event and it could happen again at any time, (as we saw with the recent report of a space rock exploding over the Bering Sea a little while ago).
https://www.news.ucsb.edu/2019/019375/day-world-burned
https://www.news.ucsb.edu/2019/019375/day-world-burned