ELOY, Ariz. -- 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 that in the seconds leading up to the impact "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 other people 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.
The identities of the victims are not being publicly released until authorities have notified their next of kin, according to the Eloy Police Department's release.
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.
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