This link takes you to a news report that summarizes the preliminary accident report by the NTSB including information from the surviving pilot.
The MD-530 helicopter with two pilots aboard was conductiing tactical training at the Blackwater Training Facility when it crashed. The Instructor Pilot was killed in the crash.
The Pilot being trained reported to investigators the tip of a skid had gotten hung under a railing located on a "Ship Simulator" training device made up of Shipping Containers and the aircraft rolled over during an attempted takeoff from a "single skid" landing.
It sounds like a case of dynamic rollover caused by the one skid being trapped under the obstruction during take off.
Student pilot describes deadly crash