As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE FIRE LIGHT CAME ON APPROXIMATELY 5 MINUTES AFTER TAKE OFF. NO SPIKE IN TURBINE TEMPERATURE. THROTTLE BROUGHT BACK TO IDLE. FIRE LIGHT WENT OUT. EMERGENCY DECLARED. RETURNED BACK TO BASE. LANDED SAFELY WITHOUT ISSUE. TROUBLESHOOTING IN PROGRESS.