Night of the Grizzlies by Jack Olsen

Night of the Grizzlies by Jack Olsen is a work of nonfiction that chronicles the separate fatal bear maulings of two nineteen-year-old women August 13, 1967 at Glacier National Park in Montana. There had been no fatal bear attacks in the 57 years of the park prior to that night, and the book came out of a 1968 Sports Illustrated story by Olsen. It's an account of the park, the maulings, likely why they happened, and what came after.  

Despite National Park Service regulations against feeding bears, park workers would leave out garbage so bears would come rummage through it, and tourists would watch from the Granite Park Chalet. Also, there were a number of bear incidents that summer, including cases of a bear acting abnormally and aggressively near Trout Lake, which should have had the Park Service on alert and taking action. 

Much of the book centers around the Chalet, where garbage was left out for bears to create a tourist attraction, and where one of the girls was killed in a campground a quarter mile away. Julie Helgeson of Albert Lea, MN, was mauled along with her friend, who suffered serious but not critical injuries. There was a doctor who was at the chalet that tried to save Julie, but she had lost too much blood by the time she was found. Twenty miles away at Trout Lake a different bear, likely the one who had been scaring campers and acting oddly, killed Michele Koons of San Diego.

A large portion of the book recounts the events of that night, and Olsen also covers the hunts for the bears that killed the two girls. The bear that was killed near Granite Park Chalet had an injured paw that would have caused constant pain, and circumstantial evidence showed it was the bear that had killed Julie Helgeson. The bear that was killed near Trout Lake was confirmed by physical evidence as the bear that killed Michele Koons.