A pair of tourists who put a baby bison into the back of an SUV after finding it on its own at Yellowstone National Park believed the animal was abandoned and would die without their help.

The incident sparked outrage after a photo taken on May 9 of the bison standing in the back of the vehicle went viral. Park rangers said the herd subsequently rejected the calf and had to be euthanized.

"I thought it was going to be a happy ending and the calf was going to be integrated with another herd and everything was going to be fine," Shakeel Kassan said in an interview with ABC News. He and his father, Shamash Kassam, found the baby bison with its umbilical cord still attached.

"We didn't have the heart to, kind of, leave it there and let it suffer, you know, as the darkness descended," Shakeel Kassam, who lives in the Washington, D.C. area, told ABC News.

The Kassams told the news station they understood that they weren't supposed to get near the animals at Yellowstone for their own safety, however, they didn't have cell phone service at the time and had no other way to reach park rangers.

The pair was shocked and confused by the subsequent coverage of the incident, which focused on reports they had tried to help the bison because it appeared to be cold.

"The whole story was, 'We kidnapped the bison. We stole a bison. We picked up a bison because we thought it was cold,'" said Shamash Kassam, a Quebec resident who described himself to ABC News as a farmer from Africa who lived near a game reserve in his native Tanzania.

In that reserve, he said, "we pick up the fawn and give it to the rangers. And they look after it. So the thinking was that I am doing the right thing by picking up this animal and giving it to the ranger, who will look after it, you know?"

Rangers cited Shamash Kassam for disturbing wildlife.

Visitors are not allowed to get near animals at Yellowstone. According to the National Park Service, visitors are required to stay at least 25 yards away from bison and other large animals.

"Every year, visitors are gored and some have been killed," the Parks Service warned. "Bison can sprint three times faster than humans can run. They are unpredictable and dangerous."