Superintendent Dan Wenk says such attacks are rare.
Authorities identified the hiker killed Wednesday by a grizzly bear in Yellowstone National Park as a man from Southern California.
Park rangers identified the deceased as 57-year-old Brian Matayoshi, of Torrance. Rangers identified the second victim as his wife, Marylyn Matayoshi.
Many California residents from up and down the state make the trek to the famed National Park for vacations.
The attack occurred on a trail near Canyon Village near the middle of the park.
Dan Wenk, superintendent of Yellowstone National Park, said Marylyn Matayoshi appears to be the only witness to the attack.
"When they saw the bear, they started to back away the same way they had come," said Wenk. "They turned around to look. They turned, then saw the bear was full charge toward them."
Wenk said Matayoshi told his wife to run. The bear caught Brian Matayoshi as his wife took cover near a tree, Wenk said.
"The bear, in some manner, lifted her off the ground," said Wenk. "She was dropped back to the ground. She played dead, and the bear left the area."
It was the park's first fatal grizzly mauling since 1986, but the third in the Yellowstone region in just over a year.
Park officials said the bear attacked to defend against a perceived threat. They said the wife called 911 on her cell phone and other hikers in the area responded to her cries for help.
Yellowstone spokesman Al Nash said the couple saw the bear twice on their hike. The first time, they continued hiking. The second time, the grizzly was running at them and the man told his wife to run.
The woman told park officials she didn't see the bear attack her husband. When the bear went for her, Nash said, she dropped to the ground. The grizzly lifted her off the ground by the day pack she was wearing then dropped her.
The woman may have had scrapes and bruises but didn't seek medical attention, Nash said.