A woman visiting Yellowstone National Park was charged by an elk after she tried to pose for a selfie with the animal in the background.
As the tourist inched closer to the animal, her camera raised, the elk charged out of the bushes and rushed towards her.
The elk knocked the woman to the ground before backing away.
The woman was not seriously injured and picked herself up, and promised her tour guide, who had warned her against taking the photo, that she would not do that again.
“That elk had just given birth to a calf. I think the only reason she attacked was that she had a calf and she was protecting her young,” tour guide Jody Tibbitts, who has worked at the park since 1991, told ABC News.
A man can be heard in the video warning the woman that she was getting too close to the elk.
As the woman headed back to her car, she said: "It's been a long time since I've been out here. It won't happen again."
"I'm sure it won't," the man replied, laughing.
The National Park Service rules state that tourists should stay at least 100 yards away from bears and wolves, and at least 25 yards away from other animals.
Touching or feeding animals is also prohibited.
The incident comes shortly after a baby bison was euthanised after tourists put it in the back of their car and took photos of the animal.
