An airplane crashed into the Superstition Mountains about 6:30 p.m. on Wednesday evening, near the Flatiron formation.
Witnesses saw an explosion and fireball, says Channel 5 (KPHO-TV).
We tried to get in touch with Elias Johnson, spokesman for the Pinal County Sheriff's Office -- he's on his way out there, according to Fox 10 News (KSAZ-TV), which also published a viewer's photo of the fire.
UPDATE THURSDAY: Johnson tells us this morning that six people were aboard the twin-engine Rockwell AC69 when it took off last night from Falcon Field in Mesa. It had been in the air for about 15 minutes before crashing into the mountain.
Witnesses reported seeing a huge fireball.
The fuselage was found nose-down in a side-canyon.
"The tactical people are rappelling down right now," Johnson says. "Anybody alive in there would have been burned. The whole thing was full of fuel."
The crash left a family dead.
Two brothers and a sister, ages 6 to 9, and their father, the plane's co-pilot, were on board. So were a co-pilot, believed to be the plane's owner, and a mechanic.
Johnson's wasn't ready to release the names as of about 9:30 a.m. Not all of the next-of-kin had been notified.
Three search-and-rescue teams were dispatched to the scene after the crash, which happened just after 6:30 p.m.
One team found the body of a child apart from the other wreckage -- "we don't know which child," Johnson says.
The plane had refueled before leaving for Stanfield, just south of Maricopa. For reasons that are as-of-yet unknown, the plane impacted into the west flanks of the Superstition Mountains just below the Flatiron formation, he says.
Authorities have closed Siphon Draw Gully, a popular trail that leads to the Flatiron, and other trails. Lost Dutchman State Park, the site of the staging area for the rescuers, is still open to camping and day use for people who had reservations, Johnson says.
Three people who had tried to hike up and see the wreckage this morning were chased off by deputies, he adds.
Several pieces of the plane that "looked important" were taken down by deputies, including what could possibly be the plane's information recorder, Johnson says.
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Officials from the National Transportation Safety Board were due to arrive early this afternoon.
Below: AP/ABC-15 video on YouTube