Well, this is a hell of a thing:

Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883

Manterola and pals have used this to place limits on how close the fragments must have been: between 600 km and 8000 km of Earth. … This implies an average of 131 objects per hour and a total of 3275 objects in the time between observations.

Each fragment was at least as big as the one thought to have hit Tunguska. Manterola and co end with this: “So if they had collided with Earth we would have had 3275 Tunguska events in two days, probably an extinction event.”

The evidence for this seems a little thin, but it’s of course hardly an impossibility, and the results had things been a little different would have been catastrophic. A shotgun blast of cometary chunks like this would be virtually impossible for us to deal with today; 130 years ago, it would have been simply beyond conception.