from the NTSB investigative update as posted
here by fokkerjet
...
• Initial examination of the left engine revealed multiple breaches of the engine case in the area around the high pressure compressor.
• Examination of the material recovered from runway found several pieces of the high pressure compressor spool (approximately 7-8 inches in length).
...
Here is a link to a detailed diagram of a GE90. The variant is the 115, so some details and proportions will differ from the accident flight. But nonprofessionals unfamiliar with basic turbofan structure designations may find it helpful.
http://lyle.smu.edu/propulsion/Pages.../turbofan2.jpe
As lomapaseo suggested above, I think the biggest outstanding question is how this failure resulted in the release of so much fuel.