The mother bear and her three cubs were resting atop a tree in a Boulder park, just a short distance from a playground.
Wildlife officials said something probably spooked them and they ran up the tree on Friday.
It's not uncommon for black bears to wander into Boulder neighborhoods because of green spaces that lead into the foothills and the mountains.
Officials said the bears will probably come down in the dark and make their way out of town when it quiets down and when there's not a lot of people around.
