Bison have gored two more people in Yellowstone National Park, bringing to four the number of gorings in the park this summer.

In the most recent incident, a 68-year-old woman from Georgia was hiking on the Storm Point Trail on Wednesday when she encountered a bison about 300 yards from the trailhead.

"The woman continued on the trail and as she passed the bison, it charged and gored her. A witness ran up the trail to report the incident to an interpretive ranger leading a hike in the area," a park release said. "Due to serious injuries, the woman was transported to Lake Clinic by ground ambulance and then by helicopter ambulance to a hospital outside the park."

Back on June 23 an off-duty concessions employee was gored by a bison after dark in the Lower Geyser Basin area. The 19-year-old, also from Georgia, and three friends were returning to their car after swimming in the Firehole River when they came upon the bison, which was lying down about 10 feet from them.

The woman's companion turned and ran, "but before the girl could react, the bison charged her and tossed her in the air," park officials said. "Her friends helped her to their car and drove back to Canyon Village, where all four live and work. At Canyon, the girl went to bed, but awoke a short time later feeling ill. Around one in the morning, the party called the Yellowstone Interagency Communication Center asking for medical help. Rangers transported the victim by ground ambulance to a hospital outside the park and she was released with minor injuries later that day."

Back on June 2 an Australian man was charged by a bison, which tossed him "into the air several times." Park officials said the unidentified 62-year-old was taking pictures of the bison, which was lying on the grass near an asphalt path near Old Faithful Lodge, with an electronic tablet.

"He got to within 3 to 5 feet from the bison when it charged him, tossing him into the air several times," a park release said, adding that "several people were crowding" the animal.

In mid-May, a 16-year-old exchange student was gored by a bison when trying to pose next to it for a photograph. "While hiking near Old Faithful Geyser, the teen and her exchange family joined a group of people watching a bison grazing adjacent to the trail. According to first-hand reports, the group was somewhere between three and six feet from the bison. The girl turned her back to the bison to have her picture taken when the bison lifted its head, took a couple steps and gored her," park spokeswoman Traci Weaver said.

Yellowstone officials urge visitors to remember that while many of the bison and elk in the park may appear tame, they are wild animals and should never be approached. Bison can sprint three times faster than humans can run and are unpredictable and dangerous.

Park regulations require visitors stay at least 25 yards away from all large animals - bison, elk, bighorn sheep, deer, moose, and coyotes and at least 100 yards away from bears and wolves. If a visitor comes upon a bison or elk along a trail, boardwalk, parking lot, or in developed areas, visitors must give the animal at least 25 yards by either safely going around the animal or turning around, altering their plans, and not approaching the animal.