A final, desperate move to save the four lives aboard a small, single-engine airplane by deploying its parachute wasn't enough to avert disaster, authorities said.
Instead, the aircraft, a Cirrus SR20, smashed into a soybean field Saturday morning near Crystal Lake.
"Obviously, something did go terribly wrong, but exactly what that is, I don't know," National Transportation Safety Board air safety investigator Timothy Sorensen said.
The Cirrus is registered to a flight club in Marion, Ind., but officials said they could not identify the victims as of Saturday evening.
The Cirrus SR20 has a built-in parachute that takes the weight of the aircraft, acting almost as a hot-air balloon. Such features are normally only used under "catastrophic" circumstances, Sorensen said.
Experts say such devices have to be deployed at the right altitude and time to be effective.
Among those rushing to the accident site was Darren Smith, who knew instantly his good intentions were for naught.
"There was nothing anyone could do for any of those people," Smith said.
Smith, who owns Cal and Shan's Tree Farm in Woodstock, was outside working when he heard an airplane in trouble about 10:30 a.m.
The aircraft broke through the clouds and plunged to earth near the tree farm, Smith said.
"I saw it a split second before it hit the ground. It was a horrific crash, pretty much nose-first into the ground. The impact was tremendous," Smith said.
His son, Cal Smith, was at a tree field to the north when he heard the impact.
"It kind of sounded like a gas pipe exploded," Cal Smith said.
Worried about his father and others working at the tree farm, he hurried over along with other witnesses.
What they saw combined the gruesome and the mundane -- bodies lying on the field along with a plastic container with popcorn and papers from the airplane.
"We tried to help, but there was no help that could be given," Darren Smith said.
The Cirrus SR20 was manufactured in 2000, according to the Federal Aviation Administration. The registered owner of the aircraft is the Marion Pilots Club in Indiana, a group of 10 individuals.
The aircraft went down west of Route 14 near Ridgefield Road.
It appears the pilot was talking to air traffic controllers at the Elgin Terminal Radar Approach Control facility before the crash. The parachute had been deployed, investigators said.
Officers responding to several 911 calls found the plane in several pieces, with the parachute snagged in a nearby tree, McHenry County Sheriff's Deputy Aimee Knop said. All the victims were pronounced dead at the scene, Knop said.
McHenry County coroner officials said the four adult victims included two males and two females, but authorities stressed that no positive identities had been made yet and said they don't expect to release names of the individuals before Monday after relatives are notified.
Officials would not confirm Indiana media reports that the victims included a Marion businessman and his two daughters.
"At least nobody got hurt on the ground," said Don Behrens, a tree farm employee, who witnessed a white stream coming from the descending airplane and a huge cloud of dust after it hit.
"I've seen a lot of stuff in my life, but I've never seen anything like this," he said.
Farmer Marvin Marquardt, who owns the property, said the parachute had caught in a burr oak tree and debris was scattered over his field.
The Cirrus "was in little pieces," he said.
The plane was operating under visual flight rules. One official said the plane flew out of Marion Municipal Airport, but the destination of the flight has not been reported, and Knop said no flight plan had been found.
There was light rain at the time of the accident, along with a cloud ceiling of about 900 feet and visibility of 1.75 miles, according to the National Weather Service. Winds were from the south.
It was the second fatal plane crash in the suburbs in the past week. Frank Kehoe, 69, of Hampshire was killed Nov. 20 when his single-engine plane crashed shortly after takeoff from an airstrip west of Elgin.
• Daily Herald staff writer Lee Filas contributed to this report