By Laura Zuckerman
(Reuters) - At least one grizzly bear attacked a hiker who was found dead and partially eaten in Yellowstone National Park in Wyoming, judging by wounds on his arms, park officials said on Saturday.
The official cause of death is undetermined but an autopsy is planned for Monday, said Yellowstone spokeswoman Amy Bartlett.
A park ranger found the hiker's body on Friday in a popular back-country area about 5 miles (8 km) from Elephant Back Loop Trail near Yellowstone Lake in the middle of the park, Bartlett said.
The Montana man had been reported missing that day after he failed to show up for work as a seasonal employee of a company that operates urgent care clinics in Yellowstone, she said.
Early results of an investigation show the hiker, whose name was withheld pending family notification, had what appeared to be defensive wounds on his forearms from an encounter with the massive, hump-shouldered bears, Bartlett said.
Tracks near the body suggested a grizzly sow and at least one cub was present and likely involved, she said.
Elephant Back Loop Trail remained closed on Saturday, a day after government wildlife biologists set bear traps and sought to recover grizzly DNA for testing, she said.
Any grizzlies trapped and found to have been involved in the attack will be killed, Yellowstone Superintendent Dan Wenk said in a statement.
"We may not be able to conclusively determine the circumstances of this bear attack but we will not risk public safety," he said.
The park recorded two deadly grizzly maulings in 2011.
The Montana man was an experienced hiker in his fifth season of working and living in Yellowstone, which spans more than 3,400 square miles (8,800 square km) of Wyoming, Montana and Idaho, Bartlett said.
It did not appear he was carrying bear spray, she added.
The millions who visit the park each year are advised to carry bear spray and hike in groups to avoid encounters with the more than 700 federally protected grizzlies that roam the area.
(Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Alex Dobuzinskis and James Dalgleish)