Earlier this month, Yellowstone National Park officials issued a release warning that grizzly bears very possibly would be active in their search for food this fall and humans should be especially alert. Well, it seems the bears took that message to heart.

On Friday bears were spotted on the streets in Mammoth Hot Springs in Yellowstone National Park.

"There’s a grizzly, a lone grizzly, and a black bear with two cubs that have been walking Mammoth," Yellowstone spokesman Dan Hottle said Friday afternoon. And while the bears hadn't come into contact with any humans, he noted there had been a mauling in the Bridger-Teton National Forest south of Yellowstone earlier in the week.

Up in Glacier National Park in northern Montana, meanwhile, park officials initially said this week that the St. Mary Campground would reopen, but only to hard-sided campers due to recent bear activity. But on Friday they reversed course, saying there was too much bear activity to allow that.

"Since that (earlier) announcement, there has been increased black and grizzly bear activity in and around the campground. Efforts to haze the bears from the area have been unsuccessful," park spokeswoman Denise Germann said in a release. "For public and bear safety issues, the campground will be temporarily closed until bear activity decreases.

"At this time of year, bears are entering a phase called hyperphagia. It is a period of concentrated feeding to prepare for hibernation," she added. "This year there has been an exceptionally abundant crop of a variety of berries located in the campground, attracting bears to the area."

So if you're heading into parks in the Rockies, keep an eye out for bears.