(CNN) -- Six people, including three children, were killed when their plane crashed into rugged mountains east of Phoenix on a Thanksgiving eve trip, authorities said Thursday.
Pinal County Sheriff Paul Babeu identified the dead as a father and his three children, plus two other men. All were Arizona residents and knew each other well, he said.
The twin-engine Rockwell 690A airplane slammed into a steep cliff near the top of the Superstition Mountains at 6:31 p.m. on Wednesday, strewing debris for hundreds of yards down the 80-degree incline, Babeu told reporters.
Recovery efforts by more than 50 deputies and volunteers involved collect and preserving the remains, the sheriff said.
"No one could survive that crash," he said.
The plane had flown from Safford to Mesa, where it picked up the siblings -- ages 9, 8 and 6 -- for the Thanksgiving holiday, Babeu said.
"All of these families are just obviously heartbroken, traumatized over the loss of their loved ones so suddenly here on Thanksgiving," he said.
Federal officials were expected to begin their investigation as soon as Thursday, according to Babeu.
A man who said he witnessed the impact told CNN that a mushroom cloud of flames lit up the evening sky.
Kevin Cunningham, 44, of Apache Junction, said he was talking on the phone from his back porch and saw the crash a few miles away.
"The flames lit up the mountain," said Cunningham, adding the plane appeared to be flying level before the crash. "I didn't see where it was in distress."
CNN's Phil Gast and Tom Cohen contributed to this report.