Two bears, one a cub of a famous grizzly, died after being hit by vehicles in separate accidents in Grand Teton National Park on Sunday evening, a park spokesman said Monday.

"The first one took place around 7:30 p.m. with an adult female black bear was hit on U.S. Highway 89," Andrew White said.

She probably was between 15 and 20 years old and did not have a cub with her, White said.

"The second was a male grizzly bear cub of the year, which was hit on the North Park Road near Colter Bay some time before 10 o'clock p.m.," White said.

"Cub of the year" means a cub born in a den during the winter, and came out with an adult in the spring, he said.

The cub of the year probably was the offspring of Grizzly Bear No. 399, made famous by social media. The number was assigned to her by a research team. She was known for her fertility, often having two or three cubs at a time, which made her popular with visitors, White said.

Neither of the vehicles stopped, nor did their drivers report the incidents. These are crimes if motor vehicle crashes, especially with wildlife, go unreported, and authorities later find the perpetrators and cite them under the Code of Federal Regulations. There is nothing illegal for hitting wildlife and self-reporting the incident, White said.

"We really track closely our collisions with wildlife," he said.

About 100 large animals are killed by motor vehicles annually in the park. So far this year, 37 have been killed, which is higher than usual for mid-June.

Those numbers may rise because of the increased popularity of the parks. Grand Teton National Park's visitation is up 9 percent from 2015, White said.

"We're reminding folks to slow down, be vigilant," he said. "Be mindful of your following distance."

Anyone who has information about these incidents is encouraged to call Grand Teton National Park's dispatch number is (307) 739-3301.