By Melissa Alonso, CNN

(CNN) — A group of skydivers jumped from a hot air balloon floating over the Arizona desert just moments before it crash-landed Sunday, leaving four of its remaining passengers dead and another person critically injured, police announced.

The “devastating incident” happened around 7:50 a.m. in Eloy, a city about 65 miles south of Phoenix, the local police department said in a news release. It came down in a desert area east of Sunshine Boulevard and Hanna Road.

The aircraft was carrying 13 adults – a balloon operator, four passengers and eight skydivers, according to Eloy Mayor Micah Powell.

Shortly after all the skydivers completed their planned jump from the aircraft, “something catastrophic occurred with the balloon, causing it to crash to the ground,” said Eloy Police Chief Byron Gwaltney at a news conference.

Though the exact cause of the crash is unknown, preliminary information suggests it occurred after the balloon had an “unspecified problem with its envelope,” said the National Transportation Safety Board, which is investigating the incident.

A witness on the ground told authorities in the seconds leading up to the crash “the material of the hot air balloon was just straight up and down, and the impact was fairly, fairly large,” the mayor said.

One person died on the scene and three others died after being taken to a hospital, according to the mayor. The person who was critically injured was transported to a trauma center in Phoenix, he said.

On Monday, police identified the four victims as Chayton Wiescholek, 28, from Union City, Michigan; Kaitlynn Bartrom, 28, from Andrews, Indiana; Atahan Kiliccote, 24, from Cupertino, California; and Cornelius van der Walt, 37, originally from South Africa and residing in Eloy.

Van der Walt was the pilot, according to the Eloy Police Department.

Valerie Stutterheim, 23, from Scottsdale, Arizona, was critically injured in the incident, police said.

“We extend our deepest condolences to the families and friends of those who have lost their lives in this tragic incident and our thoughts are with Ms. Stutterheim as she receives medical care,” the police statement said.

Bartrom’s mother, Jennifer Hubartt, described her daughter as a registered nurse from Indiana who loved skydiving and adventure, according to CNN affiliate KNXV.

Hubartt said her daughter had traveled from Indiana to Arizona with friends and that she was “really enjoying the experience and having fun and seeing a new place that she had never seen before.”

“It’s kind of somber here at home. We’re crying about her on and off and talking about her on and off still trying to make it real,” Hubartt told KNXV. “She was a beautiful person, she recently became an RN and was making it on her own.”

The close-knit city has a “very large skydive community presence” and boasts a large “drop zone,” or area where skydivers can land, according to the mayor.

NTSB investigators were at the scene Sunday night documenting the crash site and examining the aircraft, which will be brought to a secure facility for further analysis in the coming days, an agency spokesperson told CNN.

The aircraft was an A-160 passenger balloon manufactured by Cameron Balloons, according to the NTSB. The model can carry a pilot and up to seven riders, the manufacturer’s website says. CNN has sought comment from Cameron Balloons.

The Eloy Police Department said it is working with the NTSB and the Federal Aviation Administration on the investigation.

“While we continue our efforts, we ask for your thoughts and support for the families and loved ones affected during this difficult time,” police said.

CNN’s Elizabeth Wolfe and Paradise Afshar contributed to this report.