As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED THE NR1 ENGINE FIRE INDICATION, ENGINE WAS SHUTDOWN AND FIRE EXTINGUISHER ACTIVATED, AN EMERGENCY WAS DECLARED AND THE ACFT RETURNED TO POINT OF DEPARTURE AND LANDED. MX FOUND EVIDENCE OF A FIRE AND A BROKEN VENT PIPE.