Some info from ORD suggests that a tire or two blew during the abort and pieces penetrated the right inner fuel tank. That would cause the huge fire event on the right side. The question will be if it was a tire failure that was caused by an uncoontained engine failure or if it was an abort for what they thought was an engine issue but was in fact a blown tire. The sounds are very similar but the indications, of course, are not. I'm sure it will all come out in the investigation.
Kudos to the crew for getting the actual evacuation done quickly and safely. That's not easy with a raging fire going on next to you.