By Tim Jimenez

PHILADELPHIA (CBS) — The investigation continues into the plane crash that killed Lewis Katz and six others over the weekend. National Transportation Safety Board officials are looking at black boxes they recovered and gave an update Tuesday.

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NTSB investigator Luke Schiada says the private jet reached a speed of 165 knots, or 190 miles per hour and information from the flight data recorder showing what a witness previously reported.

“FDR data indicated that the aircraft did not lift off the runway,” says Schiada.

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And Schiada says the pilot may have been trying to stop the plane.

“There are indications that the break pressure’s rising’s consistent with deceleration and we’re also observing tire marks on the runway,” says Schiada.

The black boxes were sent to an NTSB lab in Washington, D.C.

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Schiada says the cockpit voice recorder has two hours of audio in what he calls “good to excellent quality.” As for the cause of the crash, he says they have a lot of work to do before that’s determined.