Greg Biffle Plane Wreckage Revealed in Harrowing Footage

Investigators are still looking into the plane crash that claimed NASCAR legend Greg Biffle's life ... and, new video shows them looking for clues in the wreckage.

The National Transportation Safety Board released video of agents combing through the debris ... taking photos of the plane and looking in the woods surrounding the crash area.

The plane's a wreck ... broken into pieces both large and small and burned to a crisp in places. It's unclear what investigators might be able to glean from the crash site.

At a press conference held Saturday morning, officials essentially said they've not yet determined the cause of the crash.

However, the NTSB did confirm someone on the plane sent a text to a family member with the words "emergency landing" in it.

We published video of Biffle's jet crashing near a runway at Statesville Regional Airport in North Carolina ... looking like a large ball of fire as it crashed to the earth. The aircraft was supposed to fly to Florida, but turned back shortly after takeoff before the tragic crash.

Biffle, his wife Cristina, his two children -- Emma, 14, and Ryder, 5 -- Craig Wadsworth, Dennis Dutton and Jack Dutton all perished in the crash.