A grizzly bear fatally attacked a hiker in Yellowstone National Park, park officials said today.

The fatal attacked occurred when the man encountered the mother bear and her cubs a mile and a half from the start of the Wapiti Lake trail.

“In an attempt to defend a perceived threat to her cubs, the bear attacked and fatally wounded the man,” a a statement released by park officials said.

A group of hikers near the attack heard the victim's wife crying for help and used a cell phone to call park rangers.

The bears involved in the attack have not been captured. Park officials said they did not have enough initial information to determine what actions should be taken.
Initial information indicates that the mother bear behaved normally in defending her cubs and would not be killed, park spokeswoman Linda Miller said.
"If we have an aggressive bear that continually poses a threat to human safety, then we work to remove it from the ecosystem," said Yellowstone spokesman Al Nash. 

There has not been a bear-caused death since 1986, according to the Park Services.

The victim’s identity and hometown are currently being withheld.