Florida plane crash investigators say weather conditions a 'major focus,' plane may have started to break up

Federal investigators said Monday that weather conditions are a "major focus" of their investigation into the fiery private jet crash that killed nine people in South Florida.

National Transportation Safety Board (NTSB) member Tom Chapman said investigators have preliminary indications that the Learjet 60 was breaking apart before it crashed in a Palm Beach County neighborhood Sunday afternoon.

"We do have some indication that the aircraft was breaking up before impact," Chapman said during a Monday news conference.