Witnesses described a bloody and charred scene. Officials declined to identify the four victims pending family notification.
Federal Aviation Administration spokesman Tony Molinaro said the Cessna 421-C departed Joe Foss Field for Rapid City at 2:24 p.m. Shortly after, the small, two-engine plane began experiencing problems and started circling back to the airport before it slammed into the ground, killing the pilot and three passengers.
Sioux Falls Fire Chief Jim Sideras said investigators do not yet know what problems the plane was experiencing or whether the pilot radioed for help. The plane was a charter, and Sideras said he did not know who the owner was.
FAA records indicate it was registered to an Ipswich, S.D., business. Attempts to reach that business were unsuccessful Friday.
"Right now, it's a shell of a plane. It's essentially just a charred area right now," Sideras told reporters gathered in a parking lot overlooking the crash site. "That amount of fire is not survivable."
John Dahlin, 28, of Sioux Falls, was driving to work when he saw the plane out of the corner of his eye. Dahlin said he thought the pilot was performing a stunt before he realized the plane was out of control.
"It was a spinning, straight-nosed dive into the ground," he said.
A split-second later, the plane burst into flames, he said. Dahlin drove closer to the site to try to help as he called 911.
Jack Sundet, 54, a retired Sioux Falls firefighter who used to work at the airport's crash center, said he pulled over after seeing smoke billowing from a field near the airport as he drove home from the grocery store.
Sundet said he pulled out a pair of binoculars and spotted the tail of a plane. The wreckage was compact on the ground, meaning there was no debris for emergency responders to sift through -- and likely no survivors.
"It's like the plane went from nose to tail right into the ground," he said. "The tail was the only thing that was still intact. Everything else was engulfed in flames."
Sioux Falls Mayor Mike Huether said ambulances responded quickly but there was "no chance for survival."
Molinaro said the FAA would investigate and forward its findings to the National Transportation Safety Board. According to NTSB data, the last aviation crash it investigated in Sioux Falls was in 1984.