After a grizzly bear attacked and killed a hiker Wednesday, Yellowstone National Park has closed all of its backcountry campsites and trails as rangers investigate.
Park officials believe Brian Matayoshi, 57, of California, disturbed a grizzly sow and her cubs while hiking with his wife. When the couple spotted the bear, they turned and walked away. But when they looked back at the bear, they saw it was running towards them. Next, they made what proved to be a fatal mistake, they ran.