On Sunday, the identities of four family members from Oregon who tragically perished in a helicopter crash in Arizona were confirmed. The accident occurred when their private helicopter collided with a slackline stretched across a canyon.

Piloting the MD 369FF helicopter was 59-year-old David McCarty, who was accompanied by his nieces—Rachel McCarty, 23, Faith McCarty, 21, and Katelyn Heideman, 22—on a scenic flight, as reported by The Arizona Republic. Tragically, David was set to exchange vows this upcoming weekend, according to People.

An observer witnessed the helicopter striking the slackline, also referred to as a highline, which spanned Telegraph Canyon, situated just south of Superior and roughly 64 miles east of Phoenix. The incident occurred around 11 a.m. on Saturday, prompting the observer to notify emergency services, the Pinal County Sheriff’s Office revealed in a statement. Deputies on the scene “visually located a single crashed private helicopter” that had departed from Pegasus Airpark in Queen Creek, Arizona, approximately 29 miles from the canyon. It took several hours for both local teams and Federal Aviation Administration (FAA) investigators to trek to the remote crash site.

In response to the crash, the National Transportation Safety Board and the FAA have imposed a temporary flight restriction over the area while they conduct an investigation.

The Pinal County Sheriff’s Office stated, “Initial findings suggest that a recreational slackline, exceeding one kilometer in length, was suspended across the mountain range.”

Slacklines, typically 1- to 2-inch-wide strips of nylon or polyester webbing, are tensioned between two elevated points, often trees. As described by Slackline U.S., the activity of traversing these lines blends balance training, recreation, and “moving meditation,” making it both a sport and an art form.

A line like the one across the canyon requires posting a Notice to Airmen with the FAA, and a tightrope obstruction warning to pilots was in place when the crash occurred, The Arizona Republic reported.

Another group, the International Slacklining Association, noted that no highliners were present when the helicopter hit, and said aviation markers had been attached to the line.

David McCarty owns La Grande, Ore.-based Columbia Basin Helicopters, the La Grande Observer reported, as well as a home in Queen Creek, a Phoenix suburb. A family member noted on social media that he had been piloting helicopters for more than 40 years.

“They were all so loved,” Katelyn Heideman’s mother and Rachel and Faith McCarty’s aunt, Mary Jane Heideman, texted to The Arizona Republic. “The girls had such bright futures. It’s just hard to fathom this.”

“All the love and support is welcome,” wrote Elizabeth Gallup, who said in a social media post that Rachel and Faith were her “two baby sisters” and that McCarty and Heideman were her uncle and cousin. “We truly have no words right now. They are all in heaven together.”

With News Wire Services