CARLSBAD -- The roar of a heavy-duty saw cutting up the scorched wreckage of the plane that crashed this week at McClellan-Palomar Airport split the air Thursday, as investigators continued to hone in on what caused the twin-engine Cessna Citation jet to overshoot the runway.

Four people died in Tuesday's crash.

"At this point all there is really (is) wreckage recovery," said Debra Eckrote, the National Transportation Safety Board acting regional director in Seattle, in a phone interview. "They're starting to review the radar data, (air) traffic communications. Now it's a matter of looking at the data as it's coming in and evaluating that."

Authorities said earlier that a preliminary investigation didn't reveal any signs of trouble on the privately owned business jet before it touched down about 6:40 a.m. Tuesday halfway down Runway 24.

The plane, arriving from Hailey, Idaho, then smashed through navigation equipment at the end of the runway, came over a hillside embankment, slammed into a mini-storage building and burst into huge flames at the north end of Palomar Oaks Way, officials and witnesses said.

Pilot John C. Francis of Boise, Idaho; co-pilot Anthony A. Garrett of the Hailey area, and passengers Janet Shafran of Ketchum, Idaho, and Frank Jellinek Jr. of Rye, N.H., died in the crash, according to the safety board and Sun Valley Aviation in Hailey. The plane had taken off two hours earlier.

David A. Ogren of Reno, Nev., had a truck in the storage building. He was among those who have expressed sympathy and concern this week for the victims and their loved ones.

"We're the ones who got out of it lucky," Ogren, 64, said Thursday, looking toward the runway embankment and wreckage. "The folks in the plane are the sad case. I imagine that ride down that hill was pretty awful."

Investigators have found the plane's cockpit voice recorder, still to be analyzed, and noted that there didn't appear to be anything unusual about the engines so far.

However, there was no explanation yet for why the plane's landing gear was down but the thrust reversers that would have slowed the Cessna for a landing were still stowed away.

Authorities said it could take up to a week to clear the crash site and four to six months for an investigation report.

Blood samples, the pilot's record, information about his last 72 hours, plane maintenance records and the age of the aircraft are among the materials and information being gathered, in addition to weather data and communications tapes.

Terry Williams, NTSB spokesman in Washington, D.C., said the main fuselage of the light jet will be taken to a facility near Lancaster for further examination. The plane's engines will be shipped out for inspection and teardown, probably back East, he said.

Cessna may be involved in that to provide technical expertise, Williams said, "but our people will be taking the lead on that."

Contact staff writer Jo Moreland at (760) 740-3524 or jmoreland@nctimes.com. To comment, go to nctimes.com.