Four of the victims of the 3:35 p.m. accident were aboard the two aircraft that crashed about a mile from Corona Municipal Airport, according to the National Transportation Safety Board. The other was killed on the ground by debris that fell from the aircraft, according to the Federal Aviation Administration.
The cause of the accident, which occurred under clear skies, was not immediately known, NTSB investigator Wayne Pollack told reporters at a late-night news conference. The names of the dead were not released Sunday night.
"The severity of the impact is fairly high," Pollack said.
FAA spokesman Allen Kenitzer said preliminary reports indicate that both aircraft were single-engine planes. One was identified as a two-seat Cessna 150; the other, a Cessna 172.
Pollack said two of the occupants of the Cessna 150 were ejected after the collision, one landing on a used car and the other landing in a lot. The two occupants of the other aircraft were found inside its wreckage at a Nissan dealership.
Witness Doug Champion said he was pulling into a supermarket parking lot just before the accident when he saw the two aircraft a mile or so away on the horizon.
"They looked like they would run into each other," said the off-duty Orange County sheriff's deputy. Champion thought it might be an optical illusion -- that the two planes might look close but actually be at different altitudes.
An instant later, however, he saw the northbound plane strike the other aircraft, Champion said.
It reminded him of an automobile collision. "It was almost like what you see in a T-bone traffic accident if someone runs a red light," he said.
"There was no explosion or fire" he said. "They just hit, broke up and fell from the sky."
Another witness, Lourdes Fajardo, said she was passing the dealerships when she saw the two planes just before they collided.
The impact destroyed one plane and left the other with its wings clipped, spiraling to the ground, she said.
"I saw the planes hit," Fajardo said, her voice cracking with emotion. "And when you see one disintegrate and the other go straight down with no wings . . . " she said, unable to continue.
Distraught, Fajardo drove home immediately, then, regaining her composure, returned to the accident scene and spoke to investigators.
Hours later, the images of the planes and the victims haunted her.
"To think they were alive and then they were gone," she said, choking up.
Debris from the collision landed on automobile dealerships in the 2500 block of Wardlow Road, according to authorities.
At an evening briefing, Corona police said most of the debris was scattered near the dealerships in an area 300 yards long by 300 yards wide. A second debris site was located about 1,000 yards from the car dealerships.