The driver who struck and killed a famous grizzly bear south of Grand Teton National Park earlier this week was not speeding and the bear's death was an accident, law enforcement officers said Friday.

The death of grizzly No. 399 on Tuesday night in the Snake River Canyon south of Jackson saddened tourists, wildlife biologists and amateur and professional photographers who for years studied and captured images of the bear and her many cubs and followed her comings and goings on social media sites.

"The bear stepped right out into the road," Lincoln County Sheriff's Patrol Lt. John Stetzenbach told the Jackson Hole News & Guide on Friday. The driver "was unable to brake in time to avoid the bear, and the collision occurred."

He said the collision "truly was an accident" and that the driver was not speeding or distracted and was not cited. The Subaru that hit the bear had to be towed from the scene, Stetzenbach said.

He declined to identify the driver, noting some online comments blamed the driver for the bear's death.

At 28 years old, No. 399 was the oldest known reproducing female grizzly in the Yellowstone ecosystem. Each spring, wildlife enthusiasts eagerly awaited her emergence from her den to see how many cubs she had birthed over the winter - then quickly shared the news online. The bear had 18 known cubs in eight litters over the years, including a litter of four in 2020. She stood around 7 feet tall and weighed about 400 pounds.

Named for the identity tag attached to her ear by researchers, the grizzly was often seen near roads in Grand Teton, drawing crowds and creating traffic jams.

Wildlife photographer Thomas D. Mangelsen previously described the bear as his muse.

"Her intelligence, her behavior, her beauty," Mangelsen told "60 Minutes" in 2018. "The fact that she's had all these offspring. There's not many bears that I know of that's had three sets of triplets."

Grand Teton bear biologist Justin Schwabedissen said Thursday that he believes her yearling cub, which was apparently not struck, will survive on its own.

Authorities said 49 grizzly bears died because of vehicle collisions between 2009 and 2023.

Grizzly bears generally live to be around 25, though some in the wild have lived for over 35 years, according to the Fish & Wildlife Service.

Before 1800, there were an estimated 50,000 grizzly bears living throughout 18 western States, including Wyoming, according to the Fish and Wildlife Service. By 1975, the population in the 48 contiguous states was reduced to between 700 to 800.

After decades of being listed as threatened in the lower 48 states under the U.S. Endangered Species Act, the population has grown to at least 1,923 grizzly bears in the 48 contiguous states.

contributed to this report.