“It was cold, it was dark, and there was a row of trees with ropes hanging off the branches,” he said. “I was thankful that we were able to get there without finding anybody hanging from those ropes.”

Image “It’s just a common thing,” said Myra Slow Bear, 15, of suicide attempts on the reservation. Her friend Alanie Martin, 14, committed suicide this year. Credit... Kristina Barker for The New York Times

Some teenagers had already congregated there, he said, and he urged them to gather around. “I counseled them, prayed with them, talked with them,” he said. They told him that “they were tired of the lives they had at home, no food, with parents all intoxicated, and some were being abused, mentally or sexually.”

Mental health professionals said they suspected that in some cases, young people might have been influenced by previous suicides. Feeling neglected, they can be attracted to the public displays of mourning that follow a death; and once they hear about the method of suicide, they imitate it.

“Contagion does occur with teenagers,” said Stephanie Schweitzer Dixon, the executive director of the Front Porch Coalition, a suicide prevention group in Rapid City, S.D. “Kids are young, they don’t think clearly, their brains aren’t fully developed. I know that things seem to be getting worse for kids. Things seem to be getting more dire.”

Ted Hamilton, the superintendent of the Red Cloud Indian School, a Jesuit school on the reservation, says suicide is an issue that schools grapple with constantly.

“To be Lakota in this world is a challenge because they want to maintain their own culture, but they’re being told their culture is not successful,” Mr. Hamilton said. Children on Indian reservations, he added, have extraordinary challenges: the legacy of oppression and forced removals, the lack of jobs and economic opportunity, and the high levels of drug and alcohol use around them.