Sounds like the kids just stumbled into a situation where they got to close to a cub and the mother reacted accordingly. Easy to do in areas with short line of sight. And they are fortunate the mother was not hungry as they often are in the spring.
Many years ago I accidentally treed a black bear cub; thought it was a big raccoon at first glance, and only realized my mistake as I heard the bushes moving behind me. It's not a comfortable situation, that's for sure.
It's pretty dumb to go in grizzly country without both.
If the wind is blowing, bear spray is ineffective.
State and federal biologists and other officials generally advocate for bear spray over firearms.
But talk to hunters. Some carry both, but all of them have a sidearm specifically for bears.
Funny how hunters always know more than government officials.