Park rangers continue to interview witnesses and hiking companions of an 18-year-old Russian woman who plunged 400 feet to her death Thursday near Inspiration Point in the Grand Canyon of Yellowstone National Park. They are calling the fatal incident an accident, though it remains under investigation.

Maria “Masha” Sergeyevna Rumyantseva of Kaliningrad, Russia, was hiking the North Rim Trail with three other acquaintances. She ventured off trail onto a loose rock promontory, which quickly gave way beneath her, said Yellowstone Park spokesman Dan Hottle.

“Rangers with the assistance of ground spotters and a Teton Interagency helicopter observed the woman’s body resting approximately 400 feet down the canyon wall,” said a Yellowstone Park news release. “They concluded that she had sustained non-survivable injuries.”

By then it was getting dark. Using a helicopter, her body was recovered around noon the next day, said the release.

Thursday was Rumyantseva’s first day in Yellowstone. She was hired by Xanterra Parks and Resorts, the park’s concessionaire. Hottle said he does not believe she had been assigned a specific location to work at.

Inexperienced to hiking, Rumyantseva may have been overly eager, like someone dashing down to the beach, Hottle said.

Staying on posted, designated canyon rim trails is a must due to the instability of loose soil and rock near ledges, said the release.

Trails around the canyon rim and elsewhere in the park have clearly marked signs saying to stay on the trails. Hikers must stick to designated paths and use common sense, Hottle said.

“We’ve had around seven (deaths in the Canyon area) since 1985,” Hottle said.

The most recent deaths were in May 2010 when two Bozeman, Mont., ice climbers fell 300 feet while scaling Silver Cord Cascades, Hottle said.