Bear encounters are worse now in the Sierras than I've ever seen. Apparently between the drought and all the fires, bears have very little habitat left to feed in, so they are crashing the campgrounds like it's their only option. And with all the new campers, they are being quite successful. I was in Kings Canyon NP for a couple weeks in early July, and the bears would start raiding around 6pm, 2 or 3 bears at a time. For some unknown reason, the new campers think that setting off their car alarms is going to scare the bears away. Nope! After things had calmed down, I was sitting in my campsite in a lawn chair when I was surprised by a bear sneaking up behind me and "nosing" my arm. It was a tall, lanky, scruffy tan thing, but it moved on quickly when I shouted at it. Things are definitely getting weird.
And yes, black bears can kill, especially in territory where they overlap with brown/griz. My brother was hanging out with the 4th victim when this notorious attack happened (2 killed, 2 others severely mauled):