Had a neighbor, who when young had married local Indian girl, had 3 kids, village gave them land across the river, built cabin; then his Indian wife went back to her people and the alcohol. The guy fell apart. Anyway, he'd take canoe across the Yukon, sit down and ponder what had happened to his life. So anyway, this guy was a pot head too and one day his dog and him went over to the cabin, walked up river bank towards cabin with his .06 and sat down burned one. When he was done,got up to walk to cabin and walked right into a sow grizz with two almost grown cubs. He shot the momma emptied the gun into her and no more ammo. The two cubs kept circlin him and he said his dog's barking is why he's here today. Cubs knew their momma was dead and didn't like it. They just didn't have to guts to charge my neighbor without their momma there. After a few hairy minutes, the cubs wondered off into the woods. True story and the neighbor says he was high as heck the entire time,nuts.
Salmon in the alders on game trail along creek often was from a week or two before, but I bet that's what happened to those kids. They probably didn't put two and two together, no joke. I see grizz playing in deep holes in creeks from time to time, bobbing up and down, splashing around, no joke.
I have had them bluff charge me countless times when the cubs were by her side, but they usually stop in the last 30 feet. They have a strong sense of self preservation when they have cubs to care for. I would hate to kill a protective mother for no reason.
They also charge with their head high and weave side to side. They also don't run as fast as they are capable of. This is how I gage a bluff charge.
The ones I have had to dispatch all came at me low to the ground, head down, eyes looking up. And they ripped the vegetation around them as they clawed the ground for traction. All of them were also wounded and you can see the rage and vengeance in their eyes. Their intent is unmistakable.
It is by far, the scariest thing any human can live through.