Various news outlets have more details, partly citing a Luftwaffe internal report.
According to this report, "severe problems with flight controls" occurred shortly after take off at an altitude of "around 6000 meters". Apparently, aircraft banked right and left violently. Plane didn't respond to pilots' control inputs and stalled. Crew then decided to return to SXF.
On finals, at around 300m altitude the aircraft started banking violently again. Crew tried to control the aircraft with rudder inputs. Aircraft touched ground with both wingtips, finally touching down hard but missing the runway. Afterwards, aircraft slid over grassy areas and taxiways until it came to rest somewhere on or around runway 7L.
According to a
report by Spiegel Online, investigators suspect that spoilers might have been mis-adjusted during maintenance.
The aircraft sustained "severe structural damage" to wings and landing gear, according to Luftwaffe technicians quoted by Spiegel Online. Damage to the fuselage is still being assessed, some cabin interiors came off during the accident. Might even be a write-off.