Rangers at Yellowstone National Park ticketed a pair of tourists after they put a bison calf into their car because they feared it was cold.

Karen Richardson, who was chaperoning a group of fifth-graders on a field trip, saw a father and son pull up at a ranger station with the baby bison in their SUV.

“They were demanding to speak with a ranger,” Karen Richardson told EastIdahoNews.com. “They were seriously worried that the calf was freezing and dying.”

Rob Heusevelet, one of the students’ father, said he told the men to remove the animal from their car and warned they could be in trouble.

“They didn’t care,” said Heusevelt. “They sincerely thought they were doing a service and helping that calf by trying to save it from the cold.”

Rangers arrived and ticketed the father-son tourists, who were visiting from another country.

The rangers followed the tourists back to where they picked up the calf, and the animal was released.

Tourists are required to stay at least 100 yards away from bears and wolves and at least 25 yards from other large animals, including bison, according to the National Park Service.