Three days removed from the end of school, two teenagers set off on a camping trip in the Arizona wilderness.

By the next day, both of them were dead, and the unexplained killings of the two high school friends at Tonto National Forest was still shrouded in mystery nearly a week later.

Both of the victims — Pandora Kjolsrud, 18, and Evan Clark, 17 — had been shot to death at a remote camping spot when their bodies were discovered by sheriff’s deputies on May 27, the authorities said.

They had just completed 11th grade at Arcadia High School in Phoenix and had gone camping on May 25 at a mountain in the forest, according to relatives, who said that they began to worry after they had not heard from the teenagers.

“I decided to go to the location where my son was, drove to the top and saw nothing,” Sandra Sweeney, Evan’s mother, said in a phone interview on Monday.

The authorities determined that the teenagers, whose bodies were found off State Route 87 between Mesa and Payson, Ariz., had died on May 26.

“At this time, the circumstances surrounding their deaths are being treated as suspicious,” the sheriff’s office said in a statement, adding that they were treating the killings as homicides.

A spokesman for the sheriff’s office, Sgt. Joaquin Enriquez, said in an email on Monday that the bodies had been found near Mount Ord, a mountain in Tonto National Forest on the northeastern edge of the county. People camp in that area because there are no developed campgrounds.

Officials did not release further details about the killings, citing the continuing investigation.

Simone Kjolsrud said in a brief phone interview on Monday that her daughter had been a student at Arcadia High School in Phoenix.

Pandora gravitated to the outdoors and played several musical instruments, according to a GoFundMe page created for her funeral expenses.

“The outdoors is where she truly felt at home,” the page said. “She loved camping, horseback riding, kayaking and hiking with friends and family.”

On Camelback Mountain, where the two teenagers were said by those who knew them to have watched sunsets together, their friends set up a memorial.

According to a GoFundMe page set up for Evan’s family, he enjoyed photography, cars, concerts and traveling.

Ms. Sweeney, his mother, said she and her son were close. In his last letter to her on Mother’s Day, he wrote: “You are the best mother and I’m forever in debt and grateful to you.”