Elks are generally mild-mannered and docile creatures, who spend most of their time munching on plants and mooching around. But there is one thing you should never ever do and that is to get between a mama and her baby – as some unfortunate people have learned the hard way.

The US National Park Service (NPS) had to release two statements advising the public to steer clear of wild animals in Yellowstone after two visitors were attacked by female elk in just three days. 

Charlene Triplett, a 51-year-old woman from Las Vegas, Nevada, was the first victim. Triplett, who is also an employee of the Mammoth Hot Springs Hotel on the Yellowstone Park grounds, was assaulted on Sunday by an elk mother protecting her calf, which was hiding behind some cars around 6 meters (20 feet) away. According to the statement, the elk reared up and kicked Triplett three times with its front legs. Triplett received serious injuries and had to be sent to the trauma department at Eastern Idaho Regional Medical Center for treatment.

The second person attacked was Penny Allyson Behr, a 53-year-old woman from Cypress, Texas. She was ambushed on Tuesday while walking between two cabins. Behr tried to back away but the elk mama was persistent and hit her in the head and torso. Behr also had to be taken to a hospital. 

There may have been two different elks involved in two separate incidents, which just so happened to be, coincidentally, eerily close together. Or there is one very protective mother roaming Yellowstone right now. The NPS is unsure.

They did, however, issue a warning, advising visitors: “It’s very common for cow elk to aggressively defend newborn calves and hide them near buildings and cars. Be extra cautious anywhere elk and calves are present: approach blind corners slowly and maintain a safe distance (at least 25 yards).”

Most of the time, elk are well-behaved and gentle – although they are cleverer than you think – but these kind of encounters are more likely to occur during calving season. Cow elks can behave extremely protectively (in some cases, a little too aggressively) around their offspring – and at 225 kilograms (500 pounds) they can pack a hefty punch. 

It's not just elk. Yellowstone National Park had to release another statement after one woman was gored by a bull bison after visitors crowded around the animal.

The moral of the story here: when it comes to wild animals, keep your distance.