Staff in Yellowstone National Park have had a busy summer responding to reports of bears in campgrounds, backcountry campsites and along roads.

In a Thursday news release, park officials revealed three recent incidents involving black bears that became habituated to human food. That included a June incident where a backcountry camper was bitten.

“All three bears exhibited bold behaviors, showed no fear around people, and have demonstrated food-conditioned behavior,” said the release from the Park Service.

Park officials took the opportunity to remind people to stay at least 100 yards away from bears and to store food and scented items properly.

“These incidents serve as unfortunate reminders that human carelessness doesn’t just endanger people; it can also result in a bear’s death,” the release said. “Allowing bears to obtain human food even once often leads to them becoming aggressive toward people. All of us play a role in keeping both bears and people safe.”

Two of the bears have been killed by park wildlife managers; they’ve been trying to capture the third.

In last month’s incident, a woman had been camping at a backcountry site along Little Cottonwood Creek, in the northern park of the park. That’s when a black bear bit into her tent and — although the tent and her thick sleeping bag kept the bear’s teeth from breaking her skin — bruised her thigh.

Rangers set up a decoy tent at the campsite to determine if the bear would continue the behavior. While rangers were there, the bear returned and aggressively tore up the decoy tent, Yellowstone officials say. The bear was killed on-site on June 11.

“Rangers suspect that this might have been a bear that gained access to human food in this same area in previous years,” Yellowstone officials said in the release.

Then in early July, at a backcountry campsite along the Lamar River Trail, campers left food unattended while packing up their gear. That allowed a black bear to eat approximately 10 pounds of human food. Campers who visited the same campsite the following evening had numerous encounters with the same bear. Their attempts to haze the bear away failed. Rangers moved multiple campers from the area and the bear was killed on July 10. The incident is still under investigation, park officials said.

Finally, since July 18, a black bear has caused property damage to tents and vehicles in a search for human food at the frontcountry Indian Creek Campground. Park staff actively hazed the bear from the campground and set up cameras.

“If the bear returns, managers will take appropriate actions based on the current circumstances, including additional hazing or removal [euthanization],” the release said. Yellowstone officials say they typically don’t relocate bears because  1) there are no areas in the park where a bear wouldn’t have the opportunity to injure a person or damage property, 2) surrounding states don’t want food-conditioned transplants, and 3) adult bears have good memories and could easily return to the original area.

Learn more at www.go.nps.gov/yellbearsafety.