Four adults died Friday morning after two single-engine planes collided above a remote desert area in north Phoenix, authorities said.
The identities were not released pending notification of family members.
"This is a tragic event," Phoenix police spokesman Steve Martos said at the scene. "It could have been much worse and be in a congested area where people reside."
Martos said planes frequently fly in the area because of the open airspace.
A pilot reported seeing the two small aircraft collide in midair about 15 miles northwest of Deer Valley Airport, spokesman Ian Gregor of the Federal Aviation Administration said.
Numerous 911 calls about the midair crash came in around 10 a.m., authorities said.
Fire crews went to the area and found the two planes. One plane, believed to be a Cessna, caught fire upon impact and was "unrecognizable," according to Capt. Dave Wilson of the Daisy Mountain Fire Department.
He said the plane contained two people, whose gender could not be determined at the scene, because the bodies were burnt.
Identification of these two victims will be made by the Medical Examiners Office, Martos said.
Martos said the identities of the two men in the other aircraft are known but the family has yet to be notified.
Wilson said the other aircraft, a Piper Archer III, appeared to have made a rough landing and was mostly intact. It was about 100 yards from the other plane with the two victims inside, he said.
"I thought possibly we might have survivors," said battalion Chief Gary Bernard of the Peoria Fire Department.