Preliminary reports indicate the two-engine aircraft flew from Safford to Mesa's Falcon Field to pick up three children for the Thanksgiving holiday and was headed back to Safford in southeastern Arizona, Pinal County Sheriff Paul Babeu said.
The aircraft slammed into an area of rugged peaks and outcroppings in the Superstition Mountains, 40 miles east of downtown Phoenix, at about 6:30 p.m. MST. authorities said.
Callers reported hearing an explosion near a peak known as the Flat Iron, close to Lost Dutchman State Park, Sheriff's spokeswoman Angelique Graham said.
Witnesses reported a fireball and an explosion.
"I looked up and saw this fireball and it rose up," Dave Dibble told KPHO-TV . "All of a sudden, boom."
Sheriff's spokesman Elias Johnson said the body of one child was recovered late Wednesday night from the crash scene, but additional details weren't released.
No names were immediately released. The children reportedly were between the ages of 5 and 9. A pilot, a mechanic and another adult were also on board, Babeu said.
Rescue personnel used infrared devices to search for bodies, but had not been able to detect any sign of movement, according to Johnson.
"It does not look promising," Babeu said at a news conference. "We will search throughout the night."
Rescue crews flown in by helicopter to reach the crash site reported finding two debris field on fire, suggesting that the plane broke apart on impact.
"The fuselage is stuck down into some of the crevices of this rough terrain, and we're doing our best at this point in the darkness," Babeu said. "This is not a flat area, this is jagged peaks, almost like a cliff-type rugged terrain."
Video showed several fires burning on the mountainside, where heavy brush is common. Flames could still be seen from the suburban communities of Mesa and Apache Junction hours after the crash.
The region is filled with steep canyons, soaring rocky outcroppings and cactus. Treasure hunters who frequent the area have been looking for the legendary Lost Dutchman mine for more than a century.
Some witnesses told Phoenix-area television stations they heard a plane trying to rev its engines to climb higher before apparently hitting the mountains. The elevation is about 5,000 feet at the Superstition Mountains' highest point.
Calls to Falcon Field, which mostly serves small, private planes, weren't immediately returned Wednesday night.
Federal Aviation Administration spokesman Allen Kenitzer said the Rockwell AC-69 was registered to Ponderosa Aviation Inc. in Safford. A man who answered the phone Wednesday night at Ponderosa Aviation declined comment.
Kenitzer said the FAA and National Transportation Safety Board would be investigating the cause of the crash.