The authorities of the Yellowstone National Park are warning the public to keep their distance from wild animals in the popular park.  Two tourists last week placed a newborn baby bison calf in their car reportedly to "keep it warm."

Charissa Reid, a public affairs specialist for Yellowstone National Park talks about the situation.
"The rangers on scene did a heroic job trying to get that bison to go back to the herd nearby, even using lights and sirens on their vehicles to get it to move away from the road and reunite with the other buffalo," Charissa Reid, tells PEOPLE. "But with no idea of where the calf came from or which mama bison it belonged to, there wasn't much else they could do. The baby buffalo had to be put down."

The calf couldn't be placed in a zoo or animal farm, Reid says, because park regulations prohibit moving wild animals out of Yellowstone. 

"It would have had to go through months of quarantine to be monitored for brucellosis (a bacterial disease in cattle and buffalo that can infect humans)," she says. "Our job here is not to rescue animals, but to maintain the ecological processes and integrity of this wild place. Yellowstone isn't a zoo." 

"Unfortunately, there was nothing more that could be done and the baby bison had to be euthanized when it caused a dangerous situation by continually approaching people and cars along the roadway," Reid tells PEOPLE. 

"Park regulations say that people need to stay at least 25 feet away from wildlife (a distance of 100 feet is required for wolves and bears)," she says, "and that is at the heart of this problem. If these people had kept their distance and contacted law enforcement, none of this would have happened." 

Tourists often feel comfortable around bison, she adds, "because they feel like they're harmless cows. But last year, we had five incidents where people were gored and seriously hurt because they got too close. Bison is very protective of their young and can be very aggressive." 

Their lumbering appearance is deceiving, she says, because they can also move fast, running up to 40 mph. Besides the situation last week, Yellowstone authorities also in recent weeks had to deal with a visitor who was caught on video trying to pet an adult bison and a group of tourists who posed for pictures with the herd at an unsafe distance. 

"I've certainly never seen it happen before," says Reid. "People need to know that bison injures more visitors to Yellowstone than any other animal. Something like this shows why we have regulations to keep wildlife and people apart."