As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKE OFF, AT APROXIMATELY 500 FT AGL, EXPERIENCED A LOUD BANG FROM THE LEFT ENGINE. THE ENGINE ROLLED BACK AND EGT WENT TO 659 AND FLASHING. COMPLIED WITH QRH FOR COMPRESSOR STALL. LANDED WITH REDUCED THRUST LANDING QRH CHECKLIST. AN EMERGENCY WAS DECLARED.