I heard on a local radio show moments ago, that an eyewitness (or three actually) is claiming they saw fire from an engine prior to impact. Take this, of course, with a grain of salt.
not significant when there is an aircraft upset, the engines often get starved of air and surge.
Although in this case it's just as likely that the flash was from a nav light.
The factual which trumps all eye witnesses is the statement by the NTSB that the engines were at full power as the pilots tried to pull out of the stall.