A crew was working to remove the remains from the aircraft at Santa Monica Airport, said Betsy Magdaleno, an investigator with the Los Angeles County coroner's office.
The twin-engine Cessna 525A crashed shortly before sunset Sunday as it arrived from Hailey, Idaho.
Mark Benjamin, CEO of Santa Monica-based Morley Construction, and his son, Luke Benjamin, a senior project manager with the company, were believed to be aboard the aircraft, Vice President Charles Muttillo told The Associated Press.
The pilot did not report any mechanical trouble before landing.
"There was no communication with the pilot indicting there's a problem with the aircraft at any time during the flight," Van McKenny, lead investigator with the National Transportation Safety Board, said Monday.
Cranes had to be brought in to lift the wrecked building off the plane before efforts could begin to retrieve remains and the cockpit voice recorder.
The investigation and release of information were very likely to be slowed by the federal government shutdown that began late Monday for the West Coast.
Investigators were to gather all evidence that could not be preserved from the active accident scene and then stop their work, NTSB spokeswoman Kelly Nantel said shortly before the shutdown went into effect.
There would be no news conferences or other public communications, Nantel said, as the federal agency focuses solely on identifying major safety issues.
Mark Benjamin spent time in the Sun Valley area of Idaho since his youth and served on the board of directors of the Idaho Conservation League, according to the executive director of the organization, Rick Johnson. He described Benjamin as "an extraordinary, thoughtful businessperson who brought a lot of passion and energy to our organization."
Johnson said Benjamin typically piloted a plane between the two states but did not know if he was at the controls Sunday.
McKenny said that after touching down, the pilot "veered off the right side of the runway and then as he continued down, the turn got sharper and sharper."
The plane crashed into a row of five connected hangars about 400 feet from the end of the 5,000-foot runway, where it caught fire.
One hangar collapsed, its steel trusses crossing over the plane and the sheet metal shell wrapping around it, McKenny said. Two other hangars received minor damage.
Fire crews responded quickly because their station was almost directly behind the accident site.
Still, "this was an unsurvivable crash," Santa Monica Fire Department Capt. John Nevandro said Sunday night.
Santa Monica Airport's single runway sits amid residential neighborhoods of this city of more than 90,000 on the Pacific Ocean. The city and nearby residents have expressed fears that certain types of jets with fast landing speeds could overshoot the runway and crash into homes.